Three observation posts P,Q and R are such that Q is due east of P and R is due north of Q. If |PQ| = 5km and |PR| = 10km, find |QR|
A
5.0km
B
7.5km
C
7.6km
D
8.7km
Verified Correct Answer: D.
Step-by-Step Mathematical Solution
\((PR)^2 = (PQ)^2 + (QR)^2\)
\(10^2 = 5^2 + (QR)^2\)
\((QR)^2 = 100 - 25\)
\(QR = \sqrt{75}\)
= \(8.660\)
\(\approxeq\) 8.7 km
Source: Myschool Past Questions Archive (Record #26499)