Question

Which of the following is a counter example for the hypothesis all parallelogram are rectangle

Answer 1

Answer:

A non-square rhombus is not a rectangle.

Step-by-step explanation:

A parallelogram is a quadrilateral (four-sided figure) that has two pairs of parallel sides.

A rectangle is a parallelogram with four right angles.

If a parallelogram does not have four right angles, then it is not a rectangle.  However it is still a parallelogram, as it has two pairs of parallel sides.

Answer 2

An example of it being incorrect:
parallelogram means a four-sided plane rectilinear figure with opposite sides parallel. 

an example of it being correct: a rectangle can be a square