Cos(3п/2-а)+cos(п+a)/(2sin(a-п/2)cos(-а)+1) ! п - - вопрос №299872432221 от 123456445 10.08.2020 03:35

Question

Алгебра: Cos(3п/2-а)+cos(п+a)/(2sin(a-п/2)cos(-а)+1) ! п - это пи!

123456445 · Answer

=( - sin a - cos a) / (2 *(-cos a)* cos a +1) =
= -(sin a + cos a) / ( 1 - 2 cos^2 a) =
= - (sina + cos a) / (sin^2 a + cos^2 a - 2 cos^2 a) =
=- (sin a + cos a) /(sin^2 a - cos^2 a) =
= - (sina + cos a) /(sin a + cos a)(sin a - cos a) =
=- 1/(sin a - cos a) = 1/ (cos a - sin a).