Question

Using opposite angles test for parallelogram, prove that every rectangle is a parallelogram.

Answer 1

At firstwe can easily prove that ABM ≡ CDM using the SAS congruence test. (alternate angles are equal).
Hence,  ABCD is a parallelogram, because one pair of opposite sides are equal and parallel.
Thereafter, ABCD is also a rectangle, because it is a parallelogram with one right angle.

Answer 2

Step-by-step explanation:

Given : ABCD is rectangle.

To Prove : ABCD is a parallelogram.

Proof : ABCD is a rectangle.

A = B = C = D = 90°........( angle of a rectangle )

In ABCD,

A = C } Opposite angle

B = D } are congruent.

ABCD is a parallelogram.......( property of parallelogram )