What is the total of the interior angles in any triangle?

• A. 90 degrees
• B. 180 degrees
• C. 360 degrees
• D. 270 degrees

Answer: (B)

Inside every triangle, the interior angles add up to 180 degrees. You can see this by drawing a line parallel to the base through the top vertex; the two lower angles align with corresponding angles at the base, so all three angles form a straight 180-degree total. Another clear view is to drop a line from the top vertex to the base, splitting the triangle into two right triangles; each contributes 90 degrees from the right angles, and together they sum to 180. This shows the total is the same for any triangle, regardless of shape. The other numbers don’t fit: 90 degrees would leave no room for the other two angles, 360 degrees is the sum for quadrilaterals, and 270 degrees isn’t the correct total for a triangle.