Упростите выражение: (1-cos a) (1+cos a)

Question

Упростите выражение: (1-cos a) (1+cos a)

Answer 1

(1-cos a) (1+cos a) =1-cos² a=sin²a

Answer 2

=1^2-cos^a= 1-cos^2a=sin^2a+cos^2a-cos^2a=sin^2a

Comments

(1-cos a)(1+cos)=1-cos^2 a=sin^2 a