Question

☆ SUBIECTUL 1. EXERCITIUL 6.
DAU COROANA !
Va roog!

Answer 1

$cos^{2}120+sin^{2}60=\\ \\ =cos^{2}120+sin^{2}(180-60)=\\ \\ =cos^{2}120+sin^{2}120=\\ \\ =1\\ \\ \boxed{sin^{2}x+cos^{2}x=1}\\ \\ sin~x=sin(180-x)$