EM-1352

Cosine rule

E Math · Secondary 3 · Medium · Cosine rule

In

\triangle ABC

,

AB=7\text{ cm}

,

AC=10\text{ cm}

and

\angle BAC=40^\circ

. Using the cosine rule, find the length of

BC

correct to 3 significant figures.

$6.46\text{ cm}$
$5.96\text{ cm}$
$8.54\text{ cm}$
$12.5\text{ cm}$

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