What is the measure of angle 1 in a triangle?

To determine the measure of angle 1 in a triangle, you need the measures of the other two angles. In any triangle, the sum of the interior angles is always 180 degrees. Therefore, you can find angle 1 by subtracting the measures of the other two angles from 180 degrees. For example, if the other two angles measure 50 degrees and 70 degrees, then angle 1 would be 180 - 50 - 70 = 60 degrees.