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【332203】【推荐】28.2 解直角三角形及其应用-同步练习(1)B

时间:2025-01-21 12:28:01 作者: 字数:4360字
简介:

28.2 解直角三角形及其应用()

一、双基整合:

1.在下面条件中不能解直角三角形的是( )

A.已知两条边 B.已知两锐角 C.已知一边一锐角 D.已知三边

2.在△ABC中,∠C=9 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>a=5c=13,用科学计算器求∠A约等于( <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

A24°38′ B65°22′ C67°23′ D22°37′

3.在△ABC中,∠C=90°abc分别是∠A,∠B,∠C的对边,有下列关系式:①b=ccosB,②b=atanB,③a=csinA,④a=bcotB,其中正确的有( )

A1B2C3D4

4.为测一河两岸相对两电线杆AB间距离,在距A15mC处,(AC⊥AB),测得

ACB=50°,则AB间的距离应为( )m

A15sin50° B15cos50° C15tan50° D15cot50°

5.在△ABC中,∠C=90°b= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ,三角形面积为 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ,则斜边c=_____,∠A的度数是____

6

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

.在直角三角形中,三个内角度数的比为123,若斜边为a则两条直角边的和为________

7.四边形ABCD中,∠C=90°AB=12BC=4CD=3AD=13则四边形ABCD的面积为________

8.如 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 图,小明想测量电线杆AB的高度,发展电线杆的影子恰好落在土坡的坡面CD和地面BC上,量得CD=4米,BC=10米,CD与地面成30°角,且此时测得1米杆的影长为2米,则电线杆的高度约为_______米.(结果保留两位有效数字, <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>1.41 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>1.73

9.如图所示,在Rt△ABC中,ab分别是∠A,∠B的对边,c <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 为斜边,如果已知两 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 个元素a,∠B,就可以求出其余三个未知元素bc,∠A

1)求解的方法有多种,请你按照下列步骤,完成一种求解过程.

第一步:已知:a, <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ∠B,用关系式:_______________,求出:_____________ <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ____;

第二步:已知:_____,用关系式:_______________,求出:_________________;

第三步:已知:_____,用关系式:_______________,求出:_________________.[来源:学科网ZXXK]

2)请你分别给出a,∠B的一个具体数据,然后按照(1)中的思路,求出bc,∠A的值.

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

10.在等腰梯形ABCD中,AB∥CDCD=3cmAB=7cm,高为2 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> cm,求底角B的度数.

[来源:学科网ZXXK]



11.如图所示,在Rt△ABC中,∠ACB=90°CD⊥ABDAC=2 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> AB=2 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ,设∠BCD=αcosα的值.

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

二、探究创新

12.国家电力总公司为了改善农村用电量过高的现状,目前正在全 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 面改造各地农村的运行电网,莲花村六组有四个村庄ABCD正好位于一个正方 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 形的四个顶点,现计划在四个村庄联合架设一条线路,他们设计了四种架设方案,如图所示的实线部分,请你帮助计算一下,哪种架设方案最省电线(以下数据可供参 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>  <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> =1.414 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> =1.732 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> =2.236).

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>






13.在Rt△ABC中, <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>C=90°,斜边c=5,两直角边的长ab是关于x的一元二次方程x2-mx+2m-2=0的两个根,求Rt△ABC中较小锐角的余弦值.[来源:..][来源:Z#xx#k.Com]








三、智能升级

14.如图,AD⊥CDAB=10BC=20,∠A=∠C=30°,求ADCD的长.

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> [来源:Z*xx*k.Com]


15.(2006·宜昌)如图,某一时刻太阳光从教室窗户射入室内,与地面的夹角∠BPC30°,窗户的一部分在教室地面所形成的影长PE <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 3.5m,窗户的高度AF2.5m,求窗外遮阳篷外端一点D到窗户上椽的距离AD.(结果精确到0.1m

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>








答案:

1B 2D 3C 4C 5 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 45°

6  <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> a 736 887 9.略

1060°  11cosα= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

12.设正方形边长为a,则(13a <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ,(23a,(3)(2+2 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> a

4)( <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> +1a ∴第(4)种方案最省电线

13 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 14AD=5 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> +10CD=10 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> +5

15.过点EEG∥ACBP于点G

EF∥DP,∴四边形BEFG是平行四边形.

Rt△PEG中,PE=3.5,∠P=30°tan∠EPG= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

EG=EP·tan∠ADB=3.5×tan30°≈2.02(或EG= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ).

又∵四边形BFEG是平行四边形,

BF=EG=2.02,∴AB=AF-BF= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> 2.5 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> -2.02=0.48(或AB= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> ).

又∵AD∥PE,∠BDA=∠P=30°

Rt△BAD中,tan30°=  <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a>

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> =0.48× <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> (或AD= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/145/" title="推荐" class="c1" target="_blank">推荐</a> <a href="/tags/180/" title="直角" class="c1" target="_blank">直角</a> <a href="/tags/387/" title="三角形" class="c1" target="_blank">三角形</a> <a href="/tags/913/" title="直角三角形" class="c1" target="_blank">直角三角形</a> )≈0.8m),

所求的距离AD约为0.8m