FTCE General Knowledge Math Practice Test 2025 – Complete Exam Prep

An isosceles triangle is defined as a triangle that has at least two sides of equal length. This characteristic is what differentiates it from the other types of triangles listed. In an isosceles triangle, the two sides that are the same length are known as the legs, and the remaining side is called the base.

The angles opposite the equal sides are also equal, which is a key property that helps in various geometric calculations and proofs. This property makes the isosceles triangle important in both mathematical theory and practical applications, such as construction and design.

In contrast, a scalene triangle has all sides of different lengths, an equilateral triangle has all three sides of the same length, and an obtuse triangle is defined by having one angle greater than 90 degrees, which doesn't inherently focus on the lengths of the sides. Therefore, the identification of the isosceles triangle as the triangle with two equal-length sides is accurate and reflects its defining characteristics.