d. The centroid of the triangle APQR can be defined as the unique point C such that OC = 30P + 100+ 1/30R Find the Cartesian coordinates of the centroid of APQR, and show that it lies on the median MR. e. In general, if T is any three-dimensional triangle, show that the three medians of T are concurrent (i.e. they intersect at a common point). Hint: The point where the medians intersect is the centroid.