Question

学长学姐们，帮忙解决一下数学题吗

学长学姐们，帮忙解决一下数学题吗过程详细就采纳，非常感谢

Answer 1

CuA={x| -3<=x<=-1,1<x<=5}
CuB={x| -3<=x<0，2<=x<=5}
{x| -3<=x<=-1，2<=x<=5}
{x| -3<=x<0，1<x<=5}

Answer 2

（1）sin^2x/(sec^2x-1)+cos^2x/(csc^2x-1) =sin^2x/tan^2x+cos^2x/cot^2x =cos^2x+sin^2x =1 （2）题目出错了，不等于1的（3）①cos(A+B)=cos(π-C)=-cosC ②sin(2A+2B)=sin[2(A+B)]=sin[2(π-C)]=sin(2π-2C)=-sin2C ③cos(2A+2B)=cos[2(A+B)]=cos[2(π-C)]=cos(2π-2C)=cos2C （4）[1+(1-cosθ)/(1+cosθ)][1+(1+cosθ)/(1-cosθ)] =(1+cosθ+1-cosθ)/(1+cosθ)*(1-cosθ+1+cosθ)/(1-cosθ) =4/(1-cos^2θ) =4/sin^2θ =4csc^2θ