What is the sum of the interior angles of a triangle?

The sum of the interior angles of a triangle is always 180 degrees. This fundamental property is true for all types of triangles, whether they are scalene, isosceles, or equilateral. The reasoning behind this can be understood through the concept of geometric shapes and how angles behave within them.

When you draw a triangle, each angle contributes to the total measure of 180 degrees. This is observable through various methods, including drawing parallel lines and using transversal angles or by dividing the triangle into two right triangles, where the angles can be accurately measured and summed.

In contrast, the other options reflect common misconceptions or attributes of different shapes. For example, a quadrilateral has a sum of interior angles equal to 360 degrees, while a right triangle does indeed contain a right angle, but its remaining angles must still add to 90 degrees, contributing to the total of 180 degrees in combination with the right angle. Thus, the correct choice, 180 degrees, encapsulates the universal rule for all triangles.