Решение
1) sinα = 3/5 π/2 < α < π<br>cosα = - √(1 - sin²α) = - √(1 - (3/5)²) = - √16/25 = - 4/5
sin2α = 2sinαcosα
sin2α = - 2*(3/5)*(4/5) = - 24/25
2) cosα = - 4/5 π < α < 3π/2<br>sinα = - √(1 - cos²α) = - √(1 - (- 4/5)²) = - √9/25 = - 3/5
sin2α = 2*(- 3/5)*(- 4/5) = 24/25