СРОЧНО
7 cos^2 а+10sin^2 а если ctg2a=2

7соs²a+10sin²a=?;ctg2a=27cos²a+7sin²a+3sin²a=7+3sin²a=7+3(1-cos2a)/2=(17-3cos2a)/2=ctg2a=2tg2a=1/21+tg²2a=1/cos²2acos²2a=1/(1+1/4)=4/5cos2a=±2/√5=±2√5/51)(17-3cos2a)/2=(17-6√5/5)/2=(85-6√5)/102)(17-3cos2a)2=(85+6√5)/10