Question

6. The diagram on the right shows right-angled triangles POR

and PRS. Given that tan 0 =
3
4
in em, the length of
(a) PR
(b) RS
Q
9 cm
R

Answer 1

The answer is below

Explanation:

Trigonometric ratios shows the relationship between the sides of a right angled triangle and its angles. Some trigonometric ratios are:

sinθ = opposite / hypotenuse, cosθ = adjacent / hypotenuse; tanθ = opposite / adjacent.

In triangle PQR:

tanθ = QR / PQ

substituting gives:

3/4 = 9 / PQ

PQ = 9 * 4 / 3 = 12 cm

Applying Pythagoras in triangle PQR gives:

PR² = PQ² + QR²

PR² = 12² + 9²

PR² = 144 + 81 = 225

PR = 15 cm

Also in triangle PRS:

PS = (5/3)PR = (5/3)*15 = 25 cm

PS² = PR² + RS²

25² = 15² + RS²

625 = 225 + RS²

RS² = 400

RS = 20 cm