A triangle with one angle that measures exactly 90 degrees is known as what?

A triangle with one angle measuring exactly 90 degrees is known as a right triangle. This specific type of triangle is defined by its right angle, and this characteristic is fundamental to understanding the types of triangles in geometry. In a right triangle, the two sides that form the right angle are referred to as the legs, while the side opposite the right angle is called the hypotenuse.

This classification is essential because right triangles have unique properties that set them apart from other types of triangles. They adhere to the Pythagorean theorem, which states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides. This relationship is commonly used in various applications, including solving real-world problems involving distances and angles.

In comparison, an equilateral triangle has all three sides of equal length and all angles measuring 60 degrees, while an isosceles triangle has two sides of equal length and two angles that are equal. An obtuse triangle contains one angle that is greater than 90 degrees. Understanding the properties of right triangles helps in distinguishing them from these other categories, making it clear why the correct term is right triangle.