In triangle PQR, PQ=13 , QR=14 , and PR=16 . Let M be the midpoint of QR . Find PM.
What kind of triangle is it? Can we see a diagram?
Cosine rule in PQR:
\(\displaystyle \cos Q = \frac{13^{2}+14^{2}-16^{2}}{2.13.14}\; . \)
Cosine rule in PQM:
\(\displaystyle PM^{2}=7^{2}+13^{2}-2.7.13.\cos Q .\)
