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In the adjoining figure, ∠BCD = ∠ADC and ∠BCA = ∠ADB. Show that

(i) △ACD ≅ △BDC

(ii) BC = AD

(iii) ∠A = ∠B

In the adjoining figure, ∠BCD = ∠ADC and ∠BCA = ∠ADB. Show that △ACD ≅ △BDC, BC = AD, ∠A = ∠B. Triangles, ML Aggarwal Understanding Mathematics Solutions ICSE Class 9.

Triangles

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Answer

(i) In △ACD and △BDC,

Given,

∠BCD = ∠ADC

∠BCA = ∠ADB

∴ ∠BCD + ∠BCA = ∠ADC + ∠ADB

⇒ ∠ACD = ∠BDC

CD = CD (Common).

∠ADC = ∠BCD (Given)

Hence, proved that △ACD ≅ △BDC by ASA axiom.

(ii) We know that, △ACD ≅ △BDC.

We know that corresponding sides of congruent triangles are equal.

∴ BC = AD.

Hence, proved that BC = AD.

(iii) We know that, △ACD ≅ △BDC.

We know that corresponding angles of congruent triangles are equal.

∴ ∠A = ∠B.

Hence, proved that ∠A = ∠B.

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