EM-1367

Cosine rule

E Math · Secondary 3 · Medium · Cosine rule

In triangle

PQR

,

PQ = 9\text{ cm}

,

PR = 11\text{ cm}

and angle

QPR = 50^\circ

.
Using the cosine rule, find the length of

QR

correct to 3 significant figures.

8.64 cm
6.94 cm
10.9 cm
13.6 cm

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