EM-1351

Cosine rule

E Math · Secondary 3 · Hard · Cosine rule

In

\triangle PQR

,

PQ=7\text{ cm}

,

PR=10\text{ cm}

and

QR=12\text{ cm}

. Find the size of angle

PQR

to the nearest degree, using the cosine rule.

$57^\circ$
$33^\circ$
$48^\circ$
$123^\circ$

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