Question

Упростите выражение: 1+2cos(П/2-a)*cos(-a)

Answer 1

1+2sina*cosa=cos^2+sin^2+2sinacosa=(sina+cosa)^2

Answer 2

1+2cos(p/2 - a)*cos(-a)
2cos(p/2-a) = 2sin(a)
cos(-a) = cos(a)
1+2cos(a)*sin(a) = sin(a)^2 + 2cos(a)sin(a) + cos(a)^2 = (cos(a)+sin(a))^2
Либо
1+2cos(a)*sin(a) = 1+sin(2a)