coordinate geometry problem

In coordinate geometry:
Given the midpoints of the sides of a triangle: P(2,5), Q(4,2) and R(1,1)
Find the coordinates of the vertices.

And tell me how you solved it.

Greetings anon, on this wonderful evening. >>1 through >>6 are completely Phail. To solve this, one needs to simply use vectors and the parallelogram rule, i.e., let a,b and c represent the vertices of the larger triangle.

Thus, b = \stackrel{\rightarrow}{RP} + \stackrel{\rightarrow}{RQ}, c = \stackrel{\rightarrow}{PR} + \stackrel{\rightarrow}{PQ} and a = \stackrel{\rightarrow}{QR} + \stackrel{\rightarrow}{QP}.