Ответ:
x1 = 3π/4 + π*k, k ∈ Z: x2 = arctg (1/7) + π*n, n ∈ Z
Пошаговое объяснение:
7sin^2 x + 6sin x*cos x - cos^2 x = 0
делим всё на cos^2 x
7tg^2 x + 6tg x - 1 = 0
(tg x + 1)(7tg x - 1) = 0
tg x = -1; x1 = 3π/4 + π*k, k ∈ Z
tg x = 1/7; x2 = arctg (1/7) + π*n, n ∈ Z
1, 2, 3, 4, 6, 7, 9, 12, 14, 18, 21, 27, 28, 36, 42, 54, 63, 84, 108, 126, 189, 252, 378, 756
1 км2=1000000м2, 300дм2=3 м2