sin^6a+cos^6a+3sin^2acos^2a的值为?
问题描述:
sin^6a+cos^6a+3sin^2acos^2a的值为?
答
sin^6a+cos^6a+3sin^2acos^2a=(sin²a+cos²a)(sin^4a-sin^2acos^2a+cos^4a)+3sin^2acos^2a=sin^4a-sin^2acos^2a+cos^4a+3sin^2acos^2a=sin^4a+2sin^2acos^2a+cos^4a=(sin²a+cos²a)²...