Question

помогите с 13 пожалуйста

Answer 1

Ответ:

8

Объяснение:

cos^2(alph) + sin^2(alph) = 1

cos^2(alph) = 1 - 21/25 = 4/25

cos(alph) = 2/5

AC = cos(alph) * AB = 2/5 * 20 = 8