
The point P(-3,-1) is rotated around (-1,3) to Q(-5,5). The picture shows how to find the new coords by rotating the red vector to the blue vector. If you view the vectors as hypotenuses of right triangles, where the legs are the differences between the coords—3-(-1)=4 and -1-(-3)=2—you can see where the P triangle is repositioned to form the Q triangle. Hence you can work out the coords of Q. The right angle for P is 4 units below the point of rotation and 2 units to the left. After rotation, the right angle for Q is 4 units to the left of the point of rotation and 2 units above it.