In quadrilateral ABCD, ∠A + ∠D = 180º. What special name can be given to this quadrilateral?

Solution:

Given

In quadrilateral ABCD,

∠A + ∠D = 180º

We know that

The sum of co-interior angles in a trapezium is 180º

Therefore, the given quadrilateral is a trapezium.

✦ Try This: Can the angles 100º, 60º, 40º and 120º be the angles of a quadrilateral? Why or why not?

The angles given are 100º, 60º, 40º and 120º

We know that the sum of all the angles of a quadrilateral is 360º

So the sum of the given angles is

100º + 60º + 40º + 125º = 325º ≠ 360º

Therefore, 100º, 60º, 40º and 120º cannot be the angles of a quadrilateral.

☛ Also Check: NCERT Solutions for Class 9 Maths Chapter 8

---

NCERT Exemplar Class 9 Maths Exercise 8.2 Problem 4

In quadrilateral ABCD, ∠A + ∠D = 180º. What special name can be given to this quadrilateral?

Summary:

In quadrilateral ABCD, ∠A + ∠D = 180º. The special name that can be given to this quadrilateral is trapezium

---

☛ Related Questions:

• All the angles of a quadrilateral are equal. What special name is given to this quadrilateral
• Diagonals of a rectangle are equal and perpendicular. Is this statement true? Give reason for your a . . . .
• Can all the four angles of a quadrilateral be obtuse angles? Give reason for your answer