Question

For a parallelogram ABCD, AB=3cm, BC=4cm and AC=5cm. Then ABCD is a

• A. Rectangle
• B. Rhombus
• C. Trapezium

Answer 1

The correct option is A Rectangle

As measure of sides of $\Delta$ABC are 3cm,4cm and 5cm,
Since (3,4,5) is a Pythogorian triplet, by the converse of Pythagoras theorem ABC forms a right angled triangle, right angled at B.
$\angle B={90}^{\circ }$.Thus all the angles of ABCD become ${90}^{\circ }$ and AB$\ne$ BC.
$\therefore ABCD$ is a rectangle.