Question

Someone help please!

Answer 1

BC ≈ 14.7 m

Explanation:

Using the Sine rule in Δ ABC

`(AB)/(sinC)` =
`(BC)/(sinA)`

To find ∠ A subtract the 2 given angles from 180°

∠ A = 180° - (90 + 28)° = 180° - 118° = 62°

Then

`(7.8)/(sin28)` =
`(BC)/(sin62)` ( cross- multiply )

BC × sin28° = 7.8 × sin62° ( divide both sides by sin28° )

BC =
`(7.8sin62)/(sin28)` ≈ 14.7 m ( to 3 significant figures )