Answer:
16.9 units
Explanation:
You want side length PQ in ∆PQR with QR=15, PR=13.3 and angle R=73°.
Law of Cosines
The law of cosines is useful for solving a triangle with two sides and the included angle given. It tells you ...
PQ² = QR² +PR² -2·QR·PR·cos(R)
Taking the square root gives ...
PQ = √(QR² +PR² -2·QR·PR·cos(R))
PQ = √(15² +13.3² -2·15·13.3·cos(73°)) ≈ 16.9
The measure of side PQ is about 16.9 units.