ПОМОГИТЕ!!!! (cos150-sin150)^2

Question

ПОМОГИТЕ!!!!
(cos150-sin150)^2

Answer 1

=cos^2 150-2sin150*cos150+cos^2 150  = 1-2sin150*cos150=1-sin300=1-sin(360-60)=
=1+sin60=1+√3/2=(2+√3)/2