Ive got one question in which i dont know how to solve. hopefully someone can help me! it is part b which im unsure of.

A curve is such that . THe curve passes through the point

a)

Find the equation of the curve (ive already solved it to be Y = -2cos(2x - )+ 3

b) Given that the normal to the curve at point P is parallel to the line 2y - x = 3, find the X-coordinates of point P for X is between 0 and pi

thanks!