Question

设矩阵 sin2a sina+cosa

Answer 1

sina+cosa =0.5,a=sin2a=(sina+cosa)^2-1=0.25-1=-0.75

b=cos2a=cos^2a-sin^2a=（cosa+sina）（cosa-sina）=0.5（cosa-sina）=-0.5c

sin2a〈0,a在第二区间,sina-cosa〉0

c^2=(sina-cosa)^2=1-sin2a=1-a=1.75,

写结果