17 Multiple Choice 1 point 17. A pennant for the sports teams at Walter Johnson High School is in the shape of an isosceles triangle. If the measure of the vertex angle is \( 18^{\circ} \), find the measure of each base angle. \( 18^{\circ}, 144^{\circ} \) \( 18^{\circ}, 18^{\circ} \) \( 81^{\circ}, 81^{\circ} \) \( 162^{\circ} .162^{\circ} \) Clear my selection

In an isosceles triangle, the two base angles are equal. The sum of all angles in a triangle is \( 180^{\circ} \). Given that the vertex angle is \( 18^{\circ} \), we can calculate the base angles as follows: 1. Subtract the vertex angle from \( 180^{\circ} \): \( 180^{\circ} - 18^{\circ} = 162^{\circ} \). 2. Since there are two base angles that are equal, divide \( 162^{\circ} \) by 2 to find each base angle: \( \frac{162^{\circ}}{2} = 81^{\circ} \). So the measure of each base angle is \( 81^{\circ} \). Hence, the correct answer is \( 81^{\circ}, 81^{\circ} \).