Question

In ∆PQR, PQ = PR = 15 cm and QR = 18 cm. Find
COS <PQR.​

Answer 1

According to Pythagoras Theorem,

(PR)2 = (PQ)2 + (QR)2

PR2 = 82 + 62

PR2 = 64 + 36

PR2 = 100

∴ PR = √100 = 10 cm

(ii) Given :

PR = 34 cm

QR = 30 cm

PQ = ?

∠PQR = 90°