In a triangle, two angles measure 65° and 45°. What is the measure of the third angle, and why?

To solve this, use the fact that the sum of the angles in a triangle is always 180°. If two of the angles are 65° and 45°, then the third angle can be found by subtracting the sum of these two angles from 180°:

180° - (65° + 45°) = 180° - 110° = 70°.

So, the measure of the third angle is 70°. This is because the sum of the angles in any triangle must add up to 180°.