Question

In ΔIJK, the measure of ∠K=90°, IJ = 8.6 feet, and KI = 4.5 feet. Find the measure of ∠I to the nearest tenth of a degree.

Answer 1

m∠I = 58.4°

Explanation:

cos = adjacent side/hypotenuse

It is always helpful to have a picture. In your case KI is adjacent to ∠I and IJ is the hypotenuse.

So cos I = KI/IJ = 4.5/8.6

arccos (4.5/8.6) = m∠I

m∠I = 58.4°

It is necessary for you to memorize the definitions of the trig functions in order to do these types of problems. OK?