Officer Aptitude Rating (OAR) Practice Test 2025 - Free OAR Practice Questions and Study Guide

In a right triangle, the sum of the angles always equals 180 degrees. Given that one angle is a right angle, measuring 90 degrees, and another angle measures 30 degrees, we can find the measure of the third angle by using the formula for the sum of angles in a triangle.

Start with the total, 180 degrees, and subtract the measures of the known angles:

180 degrees - 90 degrees (right angle) - 30 degrees (one of the angles) = 60 degrees.

This calculation shows that the remaining angle must measure 60 degrees. Therefore, in a right triangle where one angle is 30 degrees, the other non-right angle must indeed be 60 degrees. This is consistent with the properties of right triangles and the specific relationship between angles in a triangle, particularly the special characteristics of 30-60-90 triangles, where the angles are always in the ratio of 1:2:√3 in terms of their corresponding side lengths.