Question

Find the length of side BC.
Give your answer to 3 significant figures.

Answer 1

BC ≈ 19.4 cm

Explanation:

Using the cosine ratio in the right triangle

cos71° =
`(adjacent)/(hypotenuse)` =
`(AB)/(BC)` =
`(6.3)/(BC)` ( multiply both sides by BC )

BC × cos71° = 6.3 ( divide both sides by cos71° )

BC =
`(6.3)/(cos71)` ≈ 19.4 cm ( to 3 significant figures )