Question

chapter 7 triangles ex.7.4 question no.4 class 9 cbse​

Answer 1

Answer:

Step-by-step explanation:

in triangle ADC,

AD∠DC (DC is the largest side of the quadrilateral)

∠4 ∠ ∠1 (angle opposite to longer side is greater) - 1.

     in triangle ABC,

AB∠BC (AB is the smallest side of the quadrilateral)

∠3 ∠ ∠2 (angle opposite to longer side is greater) -2

from equation no. 1 and 2, we have,

∠4+∠3 ∠ ∠1+∠2

∠C ∠ ∠A

∴ ∠A ≥ ∠C

in triangle BCD,

BC ∠ DC (DC is the longest side of the quadrilateral)

∠6 ∠ ∠8 (angle opposite to longer side is greater) -1

in triangle ABD,

AB ∠ AD (AB is the smallest side of the quadrilateral)

∠5 ∠ ∠7 (angle opposite to longer side is greater) -2

from equation no. 1 and 2, we have,

∠6+∠5 ∠ ∠8+∠7

∠D ∠ ∠B

∴∠B ≥ ∠D

Hence proved.