Question

Find X:
tangent, cosine or sine?

Answer 1

x ≈ 2.76

Explanation:

Using the tangent ratio in the right triangle

tan78° =
`(opposite)/(adjacent)` =
`(AB)/(BC)` =
`(13)/(x)` ( multiply both sides by x )

x × tan78° = 13 ( divide both sides by tan78° )

x =
`(13)/(tan78)` ≈ 2.76 ( to 2 dec. places )