# How do you find the measure of the smallest in an acute triangle whose side lengths are 4m, 7m, and 8m?

##### 1 Answer

Apr 20, 2015

The smallest angle lies across the smallest side, in this case it's the one that measures 4m.

Now recall the Law of Cosines:

In our case

Using the formula above,

from which

The angle, whose *cosine* approximately equals to

More information on the Law of Cosine you can find at Unizor by following the menu items *Trigonometry - Simple Trigonometric Identities - Law of Cosine*.