Angles A and B are supplementary. Determine the measure of angle A if the measure of angle B is 121.3°.
a) 238.7°
b) 31.3°
c) 53.7°
d) 58.7°
Since angles A and B are supplementary, their measures add up to 180°. Therefore, angle A is 180° - 121.3° = 58.7°.
So the correct answer is d) 58.7°.