Найдите значение выражения (3sinx+cosx) / (sin-9cosx) если tgx=5

3 sinx + cos x / sin x + 2 cos x = 7 / 5; ⇒5 * (3sin x + cos x) = 7 * (sin x + 2 cos x) ; 15 sin x + 5 cos x = 7 sin x + 14 cos x; 8 sin x = 9 cos x; tg x = 9/8; 1) 3 sin^2 x - 2 sin x cos x + 1 = 3 sin^2 x - 2 sin x cos x + sin^2 x + cos^2 x = 4 sin^2 x - 2 sin x cos x + cos ^2 x. 2) 2 cos^2 x + sin x cos x + 3 = 2 cos^2 x + sin x cos x + + 3sin^2 x + 3cos^2 x = 3sin^2 x + sinx cosx + 5cos ^2 x. (4sin^2 x-2sinxcosx + cos^2 x) / (3sin^2 x+sinxcosx+5cos^ x) = (4tg^2 x - 2 tg x + 1) / (3 tg^2 x + tg x + 5) = = (4 * (9/8) ^2 - 2 * (9/8) + 1) / (3 * (9/8) ^2 + 9/8 + 5) = = (81/16 - 9/4 + 1) / (243 / 64 + 9/8 + 5) = = (225/16) / (635/64) = (225/16) * (64/625) = 36/25.