Verified answer

12sin^2(a) + 7cos^2(a) = 5sin^2(a) + 7sin^2(a) + 7cos^2(a) =

5sin^2(a)+7(sin^2(a)+cos^2(a) = 5 * (0.2)^2 + 7 * 1 = 5 * 0.04 + 7 = 0.2 + 7 = 7.2

Ответ : 7.2