Зная, что tg t=a, найдите sin t cos t, sin^4 t

A) a=sin t/cos t = (sint*cost) |cos^2t

sin t * cos t = a*cos^2 t

a^2 = (1/cos^2 t) - 1 cos^2t=1 / (a^2+1)

sin t * cos t = a / (a^2+1)

B) sin^4 t = (1-cos^ t) ^2

sin^4 t = (1-1 / (a^2+1)) ^2

sin^4 t = a^4 / (a^2+1)) ^2