Question

$7 sin^{2} x-5 cos^{2}x+2=0$ РЕШИТЕ УРАВНЕНИЕ

Answer 1

7sin^2x-5(1-sin^2x)+2=0
7sin^2x-5+5sin^2x+2=0
12sin^2x-3=0
12sin^2x=3
sin^2x=1/4
sinx=1/2; sinx=-1/2
x=П/6+2Пn. x=-П/6+2Пn