College Math Placement Practice Test 2025 – Comprehensive All-in-One Guide for Exam Success!

The sum of the angles in a triangle is always 180°. This is a fundamental property of Euclidean geometry and holds true for all triangles, regardless of their type (scalene, isosceles, or equilateral).

To understand this concept better, one common method for visualizing why the angles sum to 180° involves drawing a triangle and extending one of its sides. When you measure the angles around the point where the extended line meets the triangle, the angles from the triangle and the straight angle formed by the extension will add up to 180°.

This important rule is crucial for solving many geometric problems, especially when working with different types of triangles or when calculating unknown angles. The other options, such as 360°, 90°, and 270°, do not correspond to the angles in a triangle based on standard geometric principles. Recognizing that 180° is the solution helps reinforce an understanding of triangle properties and is essential for advanced studies in geometry.