cos2x等于sin-搜答案-智慧作业帮

①原式=f(x)=2cos2x+sinx^2=2cos2x+1-cos2x/2=3/2cos2x+1/2故f(π/3)=3/2*cos2π/3+1/2=-3/4+1/2=-1/4②依f(x)=3/2c

y=2(1-2sin²x)+sin²x-4cosx=2-3sin²x-4cosx=2+3cos²-3-4cosx=3cos²-4cosx-1;再问：-

诱导公式sin（a+π/2）=cosa所以sin（2x+π/2）=cos2x

cos2x 等于多少cosx

cos2X=(cosX)^2-(sinX)^2=2*(cosX)^2-1

cos^4(x)-sin^4(x)=[cos^2(x)-sin^2(x)][cos^2(x)+sin^2(x)](其中[cos^2(x)+sin^2(x)]=1)=[cos^2(x)-sin^2(x)

再答：一定等于

cos2x/(cosx+sinx)=(cos²x-sin²x)/(cosx+sinx)=(cosx+sinx)(cosx-sinx)/(cosx+sinx)=cosx-sinx求导

谁的导数等于cos2x

1/2*sin2x再问：过程？

看图片吧

3sinx/2-cosx/2=0得到tanx/2=1/3tanx=2tanx/2/(1-tan^2x/2)=(2/3)/(1-1/9)=6/(9-1)=3/4cos2x/根号2cos(Pai/4+x)

1.∫cos(2x)/(cos²xsin²x)dx=∫cos(2x)sec²xcsc²xdx=4∫cot(2x)csc(2x)dx=2∫cot(2x)csc(2

2cos2x+sin^2x 化简

2cos2x+sin^2x=2(cos^2x-sin^2x)+sin^2x=2cos^2x-sin^2x=3cos^2x-1

是的

sinx/cosx=tanx所以sin2x/cos2x=tan2x

sin2x＋cos2x＝√2（√2＆＃47；2sin2x＋√2＆＃47；2＊cos2x）＝√2（cospai＆＃47；4sin2x＋sinpai＆＃47；4cos2x）＝√2sin（2x＋pai＆＃4

1/2sin4x

因为sin^2(X)+cos^2(X)=1所以原式=1-cos^2（x）-cos^2（x）=1-2cos^2(x)=-(2cos^2(x)-1)=-cos2x

=√2/2(sin2x*√2/2+cos2x*√2/2)-1/2=√2/2(sin2xcos45+cos2xsin45)-1/2=√2/2sin(2x+45)-1/2再问：sin2x*为什么要乘以√2

（cos²x-cos2x）/1-sin²x=[cos²x-(2cos²x-1)]/cos²x=(1-cos²x)/cos²x=ta