1. The problem asks for the sum of the interior angle measures of a polygon that is a triangle. 2. The formula for the sum of interior angles of any polygon with $n$ sides is: $$\text{Sum of interior angles} = (n - 2) \times 180^\circ$$ 3. Since the polygon is a triangle, it has $n = 3$ sides. 4. Substitute $n = 3$ into the formula: $$\text{Sum} = (3 - 2) \times 180^\circ = 1 \times 180^\circ = 180^\circ$$ 5. Therefore, the sum of the interior angles of the triangle is $180^\circ$. This means if you add up all the angles inside the triangle, they will total $180$ degrees.