In a parallelogram ABCD, if `angleA = 80^(@)` then ZB is equal to

Options

A. `80^(@)`
B. `180^(@)`
C. `100^(@)`
D. `120^(@)`

Answer

To find the measure of angle B in parallelogram ABCD where angle A is given as 80 degrees, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the properties of a parallelogram**:
In a parallelogram, opposite angles are equal, and the sum of the measures of consecutive (adjacent) angles is 180 degrees.

2. **Identify the given information**:
We are given that angle A = 80 degrees.

3. **Use the property of consecutive angles**:
Since angle A and angle B are consecutive angles in the parallelogram, we can write the equation:
\[ \text{angle A} + \text{angle B} = 180^\circ \]

4. **Substitute the known value**:
Substitute the value of angle A into the equation:
\[ 80^\circ + \text{angle B} = 180^\circ \]

5. **Solve for angle B**:
To find angle B, subtract 80 degrees from both sides of the equation:
\[ \text{angle B} = 180^\circ - 80^\circ \]
\[ \text{angle B} = 100^\circ \]

6. **Conclusion**:
Therefore, the measure of angle B is 100 degrees.

### Final Answer:
Angle B = 100 degrees.

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