Question

СРОЧНО НУЖНО РИШЕНИЄ!!!

Answer 1

Объяснение:

4)

sin(a-π/3)-sin(a+π/3) = 2sin(((a-π/3)-(a+π/3))/2)*cos(((a-π/3)+(a+π/3))/2) = 2sin(-π/3)cos(a) = -2√3/2 * cosa = -√3 * cos(a)

5)

sin(a)= -2/7

π<a<3π/2 (т.е 3 четверть)

по sin²a+cos²a= 1

cosa=√(1-(-2/7)²) = -3√5/7 (т.к π<a<3π/2, то с " - " )

tga = -2/7/-3√5/7 = 2/7 * 7/3√5 = 2/3√5 *√5/√5 = 2√5/15

6) sin(-11π/3) * cos(13π/4) = -√2/2 * (-√2/2) = 1/2 = 0,5