Question

If in a semicircle one angle is 90°, then what is the degree of the other angle?

• A. 60°
• B. 40°
• C. 30°
• D. 90°

Hint:

In a semicircle, the sum of the two angles at any point is always 180°.

Answer 1

The Correct Option is D

Step 1: Understanding the Angles in a Semicircle.
In a semicircle, the sum of the angles formed at any point on the semicircle is always 180°. If one angle is 90°, the other angle must also be 90° to maintain the total sum of 180°.
Step 2: Verifying the Options.
- Option (1): 60° is incorrect, as the total sum of angles would not equal 180°.
- Option (2): 40° is incorrect for the same reason.
- Option (3): 30° is incorrect, as it does not satisfy the angle sum rule.
- Option (4): 90° is correct because the total angle in a semicircle is 180°.
Conclusion:
Therefore, the correct answer is (4) 90°.