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In quadrilateral ABCD, AD = BC and BD = CA. Prove that:(i) ∠ADB = ∠BCA(ii) ∠DAB = ∠CBA - Mathematics

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Question

In quadrilateral ABCD, AD = BC and BD = CA.
Prove that:
(i) ∠ADB = ∠BCA
(ii) ∠DAB = ∠CBA

Sum

Solution


Given: In quadrilateral ABCD, AD = BC and BD = AC.

To Prove:

(i) ∠ADB = ∠BCA
(ii) ∠DAB = ∠CBA

Proof:

In ΔABD and ΔBAC,
AD = BC           ....(given)
BD = CA           ....(given)
AB = AB           ....(common)

∴ ΔABD ≅ ΔBAC ....(by SSS congruence criterion)

`{:(∠"ADB" = ∠"BCA"), (∠"DAB" = ∠"CBA"):}} ...("c.p.c.t.")`

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Criteria for Congruence of Triangles
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Chapter 9: Triangles [Congruency in Triangles] - Exercise 9 (B) [Page 126]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 9 Triangles [Congruency in Triangles]
Exercise 9 (B) | Q 20 | Page 126

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