Question

What is the length of the side labeled x cm?

A. 8.9 cm
B. 9.9 cm
C. 17.0 cm
D. 18.9 cm

Answer 1

A

Explanation:

using the Sine rule in the triangle

we require the third angle

third angle = 180° - 42° - 61° = 180° - 103° = 77°

then

`(x)/(sin42)` =
`(13)/(sin77)` ( cross- multiply )

x × sin77° = 13 × sin42° ( divide both sides by sin77° )

x =
`(13sin42)/(sin77)` ≈ 8.9 cm ( to 1 decimal place )