If P (Sina, COSA) is a point on the terminal edge of angle a, what is the value of a

If P (Sina, COSA) is a point on the terminal edge of angle a, what is the value of a


The abscissa of point P = rcosa = Sina, the ordinate = rsina = cosa
So r = 1, Sina = cosa
So a = 180 ° K + 45 °