QR = 9 meters
Step-by-step explanation:
This is a right angled- triangle, so we apply pythagoras theorem:
Hypotenuse² = opposite² + adjacent²
PQ² = QR² + PR²
PQ = Hypotenuse =15m
PR = opposite = 12m
QR = adjacent = ?
15² = QR² + 12²
225 = QR² + 144
collect like terms:
225 - 144 = QR²
81 = QR²
Square root both sides:
√81 = √QR²
QR = 9 meters