Question

Помогите решить ,расписав по действиям
Срочно!

Answer 1

((sin a - cos a)^2 - 1)(1 + tg^2 a) + 2ctg(pi/2 - a) =
= (sin^2 a - 2sin a*cos a + cos^2 a - 1)*1/cos^2 a + 2tg a =
= (1 - 2sin a*cos a - 1) / cos^2 a + 2tg a = -2sin a*cos a/cos^2 a + 2tg a =
= -2sin a/cos a + 2tg a = -2tg a + 2tg a = 0