In a right triangle, one of the acute angles measures $80°$. What is the measure of the other acute angle?

• A. $10°$
• B. $20°$
• C. $100°$
• D. $80°$

Answer: (A)

Verified step by step guidance

1. Recall that in a right triangle, one angle is always 90°.
2. The sum of the angles in any triangle is 180°, so the two acute angles must add up to 90° because 180° - 90° = 90°.
3. Given one acute angle measures 80°, set up the equation for the other acute angle as: \(\text{other angle} = 90^\circ - 80^\circ\).
4. Subtract to find the measure of the other acute angle without calculating the final value explicitly.
5. Conclude that the other acute angle is the difference found in the previous step, which must be one of the provided answer choices.