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【332223】1.1 锐角三角函数(1)

时间:2025-01-21 12:29:22 作者: 字数:3960字
简介:

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

1.1 锐角三角函数

一、填空题:(2×12=24)

1.Rt△ABC,∠C=90°,AB=3,BC=1,sinA=______, tanA=_______, cosA=_______.

2.Rt△ABC,∠C=90°,tanA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,sinB=_______,tanB=______.

3.在△ABC,AB=10,AC=8,BC=6,tanA=_______,sinB=_______.

4.在△ABC,AB=AC=3,BC=4,tanC=______,cosB=________.

5.Rt△ABC,∠C=90°,AB=41,sinA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,AC=______,BC=_______.

6.在△ABC,AB=AC=10,sinC= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,BC=_____.

二、选择题: (3×6=18)

7.在△ABC,已知AC=3,BC=4,AB=5,那么下列结论正确的是( )

A.sinA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> B.cosA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> C.tanA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> D.cosB= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

8.如图,在△ABC,∠C=90°,sinA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> , <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> 等于( )

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

A. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> B. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> C. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> D. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

9.Rt△ABC,∠C=90°,已知cosA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,那么tanA等于( )

A. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> B. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> C. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> D. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

10.已知甲、乙两坡的坡角分别为αβ, 若甲坡比乙坡更徒些, 则下列结论正确的是( )

A.tanα<tanβ B.sinα<sinβ C.cosα<cosβ D.cosα>cosβ

11.如图,Rt△ABC,CD是斜边AB上的高,则下列线段的比中不等于sinA的是( )

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

A. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> B. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> C. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> D. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>


12.某人沿倾斜角为β的斜坡前进100m,则他上升的最大高度是( )m

A. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> B. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

C. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> D. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

三、解答题: (58)

13.Rt△ABC,∠C是直角,∠A、∠B、∠C的对边分别是abc,a=24,c= 25,sinAcosAtanAsinBcosBtanB的值.












14.若三角形三边的比是25:24:7,求最小角的正切值、正弦值和余弦值.













15.如图,在菱形ABCD,AE⊥BCE,EC=1,sinB= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> , 求菱形的边长和四边形AECD的周长.


 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>











16.如图,已知四边形ABCD,BC=CD=DB,∠ADB=90°,cos∠ABD= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> .

:  <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> :  <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> .

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>












17.已知:如图,斜坡AB的倾斜角a,tanα= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,现有一小球从坡底A处以20cm/s 的速度向坡顶B处移动,则小球以多大的速度向上升高?

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>















18.探究:

(1)a克糖水中有b克糖(a>b>0),则糖的质量与糖水质量的比为_______; 若再添加c克糖(c>0),则糖的质量与糖水的质量的比为________.生活常识告诉我们: 添加的糖完全溶解后,糖水会更甜,请根据所列式子及这个生活常识提炼出一个不等式: ____________.

(2)我们知道山坡的坡角越大,则坡越陡,联想到课本中的结论:tanA的值越大, 则坡越陡,我们会得到一个锐角逐渐变大时,它的正切值随着这个角的变化而变化的规律,请你写出这个规律:_____________.

(3)如图,Rt△ABC,∠B=90°,AB=a,BC=b(a>b),延长BABC,使AE=CD=c, 直线CADE交于点F,请运用(2) 中得到的规律并根据以上提供的几何模型证明你提炼出的不等式.

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

参考答案

1. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> 2. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> 3. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> 4. <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> 5.40,9 6.12 7.B 8.A 9.A 10.C 11.D 12.B

13.∵ <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> , <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> .

14.设三边长分别为25x,24x,7x,7x所对的角最小,设为a,

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> .

15.在菱形ABCD,AB=BC=CD=DA.

AE⊥BC,∴∠AEB=90°.Rt△ABE,

sinB= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,

AE=5x,AB=13x,BE= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,

BC=12x+1=AB=13x,x=1.

AB=13, 即菱形ABCD的边长为13.

AE+EC+CD+AD=5x+1+13x+13x=1+31x=1+31=32,

即四边形AECD的周长为32.

16.∵cos∠ABD=  <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,BD=4k,AB=5k,

AD= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> =3k.

CCE⊥BDE,

则∠BCE= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ∠BCD=30°,从而BE= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> BC=2k.

CE= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,

S△ABD= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> AD·BD= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ·3k·4k=6k2,S△BCD= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> BD·CE= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> k2.

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>  <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>2.

17.BC=3x,则由tanα= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,AC=4x,从而AB=5x,由于小球从AB上升了3xcm, 且用时为 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,故小球上升的速度为 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> =12(cm/s).

18.探究:

(1) <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a>

(2)一个锐角的正切值随着这个角的增大而增大.

(3)∵∠DEA>∠EAF=∠BAC,即∠DEA>∠BAC,

tan∠DEA>tan∠BAC.

tan∠DEA= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,tan∠BAC= <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,

 <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> ,  <a href="/tags/179/" title="锐角" class="c1" target="_blank">锐角</a> <a href="/tags/944/" title="三角函数" class="c1" target="_blank">三角函数</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/920/" title="三角" class="c1" target="_blank">三角</a> .