Quantitative Literacy Practice Exam 2025 – Comprehensive Preparation Guide

To find the missing angle in a triangle, it is essential to understand that the sum of all interior angles in a triangle is always 180 degrees. When you have one or two angles known, you can determine the missing angle by following this principle.

Specifically, you add the values of the known angles together and subtract that total from 180 degrees. This mathematical operation gives you the value of the third angle, effectively solving for the unknown. For example, if you know two angles measure 50 degrees and 60 degrees, you’d calculate the missing angle as follows: 180 - (50 + 60) = 180 - 110 = 70 degrees.

The other methods mentioned do not reflect the basic properties of triangle angles. Multiplying the known angles, subtracting from 90 degrees, or averaging them does not align with the fundamental rule that all angles in a triangle must sum to 180 degrees. Hence, the correct approach to find the missing angle consistently adheres to subtracting the sum of the known angles from 180 degrees.