This worksheet is about finding the length of a side using the sine rule.
Look at triangle ABC below
The sine rule states that:
|sin A||sin B||sin C|
We can use the sine rule to find the length of a side when we know two angles and an opposite side.
In triangle PQR, which is not drawn to scale,
PQ = 7 cm, ∠QPR = 72° and ∠PRQ = 24°.
Use the sine rule to find the length of PR in cm to 1 dp.
First we must find ∠PQR = 180° - 72° - 24° = 84°.
Using the sine rule,
|sin 84°||sin 24°|
|PR =||7 x sin 84°|
PR = 7 x sin 84° ÷ sin 24°
PR = 17.1 cm