Can u solve this vectors question for me

3. The line segment with endpoints P( 1, 2 ) and 2( 3, 6 ) is the hypotenuse of a right triangle. The third vertex, R, lies on the line with Cartesian equation -x + 2y - 1 = 0. [10] a. Determine the coordinates of R. b. Using vectors, show that A POR is a right triangle