How many degrees are in a triangle?

In a triangle, the sum of all interior angles is always 180 degrees. This is a fundamental property of triangles in Euclidean geometry. Regardless of the type of triangle—whether it is equilateral, isosceles, or scalene—the three angles will always add up to 180 degrees. This principle allows for various calculations involving triangles, such as finding missing angles when two angles are known.

To clarify why the other options do not represent the correct sum of angles in a triangle: 90 degrees refers to the sum of angles in a right triangle, which consists of one right angle and the sum of the other two angles equaling 90 degrees. 360 degrees is the sum of angles in a complete circle, while 270 degrees does not represent the sum of angles in any type of polygon. Hence, the only valid total for the interior angles of a triangle is 180 degrees.