Найдите cos^2x .если sin^2+10cos^2x=13

Question

Найдите cos^2x .если sin^2+10cos^2x=13

Answer 1

Sin^2x+10cos^2x=13

1-cos^2x+10cos^2x=13

1+9cos^2x=13

9cos^2x= 12

cos^2x = 12/9

cos^2x= 4/3