化简sin²20° cos²80 根号3
来源:学生作业帮助网 编辑:作业帮 时间:2024/10/06 01:52:50
cos(540°-α)sin(α-360°)/[sin(-α+180°)cos(180°+α)]=cos(180°-α)[-sin(360°-α)]/[sin(180°-α)cos(180°+α)]=
解题思路:同学,这个式子是不能化为cosθ-1,利用诱导公式就可以了,但要注意平方解题过程:
解题思路:利用诱导公式和立方差公式来分解因式后约分化简。解题过程:
B用三角形内、外角关系的知识
cos^2(-α)-[tan(360°+α)/sin(-α)]=cos^2(α)+tanα/sinα=cos^2(α)+1/cosα这已经是够简的了,若还有问题可以直接HI我.
原式=(sina/cosa)*sina*cos(-a)=[(sina)^2/cosa]cosa=(sina)^2再问:谢谢能不能再问道若f(sina)=3-cos(3π/2-a),则f(cosx)=A
cos平方(θ+15°)+sin平方(θ-15°)+sin(θ+180°)cos(θ-180°)=[1+cos(2θ+30°)+1-cos(2θ-30°)]/2+sin(θ)cos(θ)=1-sin(
原式=cos[(x-25)-(65-x)]=cos(2x-90)=sin2x
cos(180°+x)*sin(x+360°)/[sin(-x-180°)*cos(-180°-x)]=-cosx×sinx/[-sin(180°+x)][cos(180°+x)]=-cosx×sin
cos^2(-α)-[tan(360°+α)/sin(-α)]=cos^2(α)+tanα/sinα=cos^2(α)+1/cosα再问:为什么直接变+了再答:sin(-a)=-sina,把负号放在前
由题意可得:cos(75°-a)=sin(15°+a)sin(45°-a)=cos(45°+a)所以cos(15°+a)sin(45°+a)-cos(75°-a)sin(45°-a)=cos(15°+
(sin²θ+2sinθcosθ+cos²θ+sinθ+cosθ)/(1+sinθ+cosθ)=[(sinθ+cosθ)²+(sinθ+cosθ)]/(1+sinθ+co
积化和差:√3*sin20cos80=(√3/2)(sin100-sin60)=(√3/2)sin80-3/4逆用二倍角公式:sin²(20)+cos²(80)=(cos80)
按照你的答案,你的题目输入有误,是化简:根号1-2sin(40°)cos(40°),原因是算术平方根是非负的.1-2sin(40°)cos(40°)=sin²40°+cos²40°
sin(α+150°)=sin(α+180°-30°)=-sin(α-30°)原式=cos[(α+30°-(α-30°)]=cos60°=1/2再问:sin可以这样转换?不可以的吧?只可以2π加减,不
sina+cosa=根2*(sina*二分之根2+cosa*二分之根2)=根2*(sina*sin45°+cosa*cos45°)——(1)=根2*cos(a-45°)=根2*(sina*cos45°
积化和差:√3*sin20cos80=(√3/2)(sin100-sin60)=(√3/2)sin80-3/4逆用二倍角公式:sin²(20)+cos²(80)=(cos80)&s
(cos^210°-cos^280°)²+sin^220°=(cos^210°-sin^210°)²+sin^220°=cos²20+sin²20°=1
sin(80°+3α)cos(35°+α)-cos(80°﹢3α﹚sin﹙35°﹢3α﹚=sin[(80°+3α)-(35°+α)]=sin(80°+3α-35°-α)]=sin(45°+2α)再问:
sin80°=cos10°sin^280°=cos^210°sin^210°+sin^280°=sin^210°+cos^210°=1