题目

已知sin(a)+sin(b)=0.5^0.5,求cos(a)+cos(b)和的取值范围

提问时间：2021-02-24

答案

已知sin(a)+sin(b)=0.5^0.5所以,[sin(a)+sin(b)]^2=sin^2(a)+sin^2(b)+2sin(a)sin(b)=0.5[cos(a)+cos(b)]^2=cos^2(a)+cos^2(b)+2cos(a)cos(b)两式相加得到0.5+[cos(a)+cos(b)]^2=sin^2(a)+sin^2(b)+2sin(a)sin(b)+co...