Question

Упростите (3cos a+sin a)^2+(cos a-3sina)^2

Answer 1

$(3 \cos(a) + \sin(a) ) {}^{2} + ( \cos(a) - 3 \sin(a) ) {}^{2} = 9 \cos(a) {}^{2} + 6 \cos(a) \sin(a) + \sin(a) {}^{2} + \cos(a) {}^{2} - 6 \cos(a) \sin(a + 9 \sin(a) {}^{2} = 9 + 1 = 10$