**Finding the Third Angle of a Triangle**

Finding the third angle of a triangle when you know the measurements of the other two angles is easy.

The sums of the interior angles of a triangle are equal to 180^{0}. To find the third angle of a triangle when the other two angles are known subtract the number of degrees in the other two angles from 180^{0}.

All you’ve got to do is subtract the other angle measurements from 180° to get the measurement of the third angle. However, there are a few other ways to find the measurement of the third angle of a triangle, depending on the problem you’re working with.

**Example:** How many degrees are in the third angle of a triangle whose other two angles are 45^{0} and 60^{0}?

**Solution:**

The three angles of any triangle always add up to be 180.

So if x, y, and z are the three angles, then x + y + z = 180.

If z is the third angle, then z = 180 – x – y.

Another way to look at this is that you start with 180 and you subtract away the two angles you know, x and y, which leaves you an amount for the third angle.

Answer: 180^{0} – 45^{0} – 60^{0} = 75^{0}