To find the supplement of an angle, we need to understand that two angles are supplementary if their measures add up to 180°.
Given that one angle measures 89°, we calculate its supplement by subtracting this measure from 180°.
Step-by-step solution:
1. Start with the total measure of supplementary angles, which is 180°.
2. Subtract the given angle measure (89°) from 180°:
[tex]\( 180° - 89° = 91° \)[/tex]
Therefore, the supplement of an angle that measures 89° is 91°.
So, the correct answer is:
○ A) 91°
