I'm not sure if this belongs here but it is a question from my calculus homework:

The points P(-2,1), Q(-6,4) and R(4,3) are three vertices of parallelogram PQRS.

a) Find the coordinates of S.

b) Find the measures of the interior angles of the parallelogram, to the nearest degree.

c) Find the measures of the angles between the diagonals of the parallelogram, to the nearest degree.

I'm not really sure how to start or what to do