smc

Question

The sides PQ and PR of triangle PQR are respectively of lengths 4 inches, and 7 inches. The median PM is 312 inches. Then QR, in inches, is:

Accepted Answer

By the Median Formula, PM = 122PQ^2+2PR^2-QR^2 Plugging in the numbers given in the problem, we get 72=1224^2+27^2-QR^2 Solving, 7=2(16)+2(49)-QR^2 49=32+98-QR^2 QR^2=81 QR=9=9