Объяснение:
Решение в приложении
1)2cos²α - 3 = 2(1-sin²α)-3 = -1-2sin²α = -1-2•0.2 = -1-0.4 = -1.4
2)3sin² a - tg² a
1+tg² a = 1/cos² a; tg²a = 1/cos²a - 1 = 1/4/25 - 1 = 25/4 - 1 = 21/4 = 5.25
sin²a = 1-cos²a = 1-4/25 = 21/25 =
0,84
3sin² a - tg² a = 2.52 - 5.25 = -2.73
