Find the angle which is equal to its supplement

Options

A. `90^@`
B. `135^@`
C. `180^@`
D. `120^@`

Explanation

To find the angle which is equal to its supplement, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Supplementary Angles**: Supplementary angles are two angles whose sum is equal to 180 degrees.

2. **Let the Angle be x**: We will denote the angle we are trying to find as \( x \).

3. **Set Up the Equation**: Since the angle is equal to its supplement, we can express this relationship as:
\[ x + x = 180 \]
This simplifies to:
\[ 2x = 180 \]

4. **Solve for x**: To find the value of \( x \), we divide both sides of the equation by 2:
\[ x = \frac{180}{2} \]

5. **Calculate the Value**: Performing the division gives us:
\[ x = 90 \]

6. **Conclusion**: Therefore, the angle which is equal to its supplement is \( 90 \) degrees.