Question

In a parallelogram abcd angle a=90degree
i)what is themeasure of angle b,
ii)write a special name of parallelogram

Answer 1

Angle b =90 degree

Name of special parallelogram is rectangle

Answer 2

Given

ABCD is a parallelogram.

∠A = 90°

To Find

i) Measure of ∠B

ii) Special name of the parallelogram.

Solution

i) ABCD is a parallelogram.

Hence, AD ║BC

⇒ ∠A + ∠B = 180° [Co-interior]

⇒ ∠B = 180° - 90°

⇒ ∠B = 90°

Similiarly, by using co-interior angle rule, we can say that all angles are of 90°

ii) The special name is a Rectangle, since all four angles are of 90°. Or it could be called a equiangular parallelogram if asked in terms of parallelograms.

Properties of Parallelograms

∞ Opposite sides are parallel.

∞ Opposite sides are equal.

∞ Opposite angles are supplementary.

∞ Adjacent angles are supplementary.

∞ Diagonals bisect each other.

∞ Diagonals cut the parallelogram into two congruent triangles.