What is the measure of the third angle in a triangle if two angles are 35° and 65°?

To find the measure of the third angle in a triangle when two angles are given, you can use the fact that the sum of the angles in any triangle is always 180 degrees. In this case, you have two angles measuring 35 degrees and 65 degrees.

First, you add the measures of the two given angles:

35° + 65° = 100°

Next, subtract this sum from the total sum of angles in a triangle:

180° - 100° = 80°

This calculation shows that the measure of the third angle is 80 degrees. Consequently, this confirms that the correct answer is 80°. Understanding this method is essential for solving similar problems involving the angles in triangles, as the principle of angle summation holds for all triangles.