CBSE Class 9 Answered

Let us join AC.

In DABC

AB < BC (AB is smallest side of quadrilateral ABCD)

2 < 1 (angle opposite to smaller side is smaller) ... (1)

In DADC

AD < CD (CD is the largest side of quadrilateral ABCD)

4 < 3 (angle opposite to smaller side is smaller) ...(2)

On adding equations (1) and (2), we have

2 + 4 < 1 + 3

C < A

A > C

Let us join BD.

In DABD

AB < AD (AB is smallest side of quadrilateral ABCD)

8 < 5 (angle opposite to smaller side is smaller) ... (3)

In DBDC

BC < CD (CD is the largest side of quadrilateral ABCD)

7 < 6 (angle opposite to smaller side is smaller) ... (4)

On adding equations (3) and (4), we have

8 + 7 < 5 + 6

D < B

B > D