# Thread: Two electricity pylons P and Q are 550m apart on the same side of a river. .(continue

1. ## Two electricity pylons P and Q are 550m apart on the same side of a river. .(continue

Two electricity pylons P and Q are 550m apart on the same side of a river. A third pylon R is on the other side of the river. Angle RQP is 62° and Angle QRP is 70°. Find by calculation the distance from R to Q to the nearest metre

2. Angle Q is 62° and angle R is 70°, so angle P is 48°.

Use the Law of Sines:

$\frac{\sin P}{p} = \frac{\sin R}{r}$
(p is side QR and r is side PQ)

Plug the numbers in:
$\frac{\sin 48^{\circ}}{p} = \frac{\sin 70^{\circ}}{550}$
and solve for p.

01

3. angel RPQ = 180° - 62° - 70° = 48°

Let d be the required distance ,

By sine rule , we have $\frac{d}{\sin{48°}} = \frac{550}{\sin{70°}}$

so $d = 435 m$