An angle in a semicircle is

Options

A. `45^@`
B. `60^@`
C. `90^@`
D. `120^@`

Answer

To solve the question "An angle in a semicircle is", we need to understand the properties of angles formed in a semicircle.

### Step-by-Step Solution:

1. **Understanding the Circle and Diameter**:
- Draw a circle and label the endpoints of the diameter as points A and B.
- The line segment AB represents the diameter of the circle.

2. **Identifying the Semicircle**:
- The semicircle is the upper half of the circle that is formed when you draw the diameter AB.
- The points on the semicircle are all the points that lie on the circle above the line segment AB.

3. **Drawing a Triangle**:
- Choose any point C on the semicircle.
- Draw line segments AC and BC, forming triangle ABC.

4. **Analyzing the Angle**:
- The angle ACB is the angle formed at point C by the lines AC and BC.
- According to the properties of circles, specifically the inscribed angle theorem, the angle subtended by the diameter at any point on the semicircle is always a right angle.

5. **Conclusion**:
- Therefore, the angle ACB is 90 degrees.

### Final Answer:
The angle in a semicircle is **90 degrees**.