Question

Exercițiul 5subiect bac

Answer 1

$sin^2 a - sin^2 b = sin(a+b) * sin(a-b)$

sin(a+b) * sin (a-b) 
(sin a * cos b+cos a * sin b)(sin a * cos b - cos a * sin b)
$sin^2 a *cos^2 b - sin^2 b *cos^2 a$
$sin^2 a * cos^2 b - sin^2 b (1-sin^2a)$
$sin^2 a(cos^2b+sin^2b) - sin^2 b$ = $sin^2 a - sin^2 b$