Question

Найдите sin²a, если tga=2

Answer 1

Если tga = 2 , то ctga = 1/2
1 + ctg²a = 1/Sin²a
1/Sin²a = 1 + 1/4
1/Sin²a = (1)1/4
Sin²a = 1/(5/4) = 1 * 4/5 = 4/5