Question

Determine the measure of the indicated angle in the following triangle:

Answer 1

Θ ≈ 58°

Explanation:

using the Cosine Rule in the triangle

cosΘ =
`(80^2+60^2-70^2)/(2(80)(60))` =
`(64000+3600-4900)/(9600)` =
`(5100)/(9600)` =
`(51)/(96)` , then

Θ =
`cos^(-1)` (
`(51)/(96)` ) ≈ 58° ( to the nearest degree )