# If a parallelogram has a right angle, is it a rectangle?

##### 1 Answer

Dec 26, 2015

Yes, a parallelogram with a right angle has all right angles and is a rectangle.

#### Explanation:

In a parallelogram adjacent angles are supplementary, that is their sum is *Geometry - Quadrangles - Parallelogram*.

Therefore, adjacent angle to the one that is equal to

Since there are two adjacent angles, both are equal to

The remaining angle is opposite to a given, and opposite angles are equal in a parallelogram. So, it is also

So, all four angles are right angles and a parallelogram is a rectangle.