A triangle with one angle of 90 degrees is called a:

A triangle with one angle of 90 degrees is called a:

• A. Isosceles Triangle
• B. Acute Triangle
• C. Equilateral Triangle
• D. Right Triangle

Answer: (D)

Recognize how triangles are categorized by their angles. If one angle measures 90 degrees, the triangle is a right triangle. That 90-degree angle creates a corner like a square corner, which is why the name “right” is used. The side opposite that angle is the longest and is called the hypotenuse. The other options describe triangles by sides or by all angles: an isosceles triangle has two equal sides, an equilateral triangle has all three sides equal, and an acute triangle has all three angles less than 90 degrees. So a triangle with a 90-degree angle is identified as a right triangle.

Recognize how triangles are categorized by their angles. If one angle measures 90 degrees, the triangle is a right triangle. That 90-degree angle creates a corner like a square corner, which is why the name “right” is used. The side opposite that angle is the longest and is called the hypotenuse. The other options describe triangles by sides or by all angles: an isosceles triangle has two equal sides, an equilateral triangle has all three sides equal, and an acute triangle has all three angles less than 90 degrees. So a triangle with a 90-degree angle is identified as a right triangle.