1) 5cos180°-3sin90°+4tg45° = -5-3+4 = -4.
2) 6sinπ+3cosπ-tg0 = 0-3-0 = -3.
3) tgα = 7.
sinα = (7/(-√(1+49))) = -(7/√50) = -(7√2)/10.
cosα 1/(-√50) = -(√2/10).
ctgα = 1/7.
4) sinα = -0,6. cosα = -√(1-0,36) = -0,8.
5) tg²β-(1/cos²β) = (sin²β-sin²β-cos²β)/cos²β = -1.
6) 3tgα*ctgα-3sin²α = 3(1-sin²α) = 3cos²α.
7) ctg²α(cos²α-1) = (cos²(1-sin²-1)/sin²α = -cos²α.