Докажите формулу cos(3pi/2+a)=sina

Question

Докажите формулу cos(3pi/2+a)=sina

Answer 1

Cos(3π/2+α)=sinα;
cos(3π/2+α)=cos(2π-π/2+α)=cos[-(π/2-α)]=cos(π/2-α)=sinα