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In the given figure, ABCD is a quadrilateral in which AB = AD and BC = DC. Prove that(i) AC bisects ∠ A and ∠ C,(ii) BE = DE,(iii) ∠ ABC = ∠ ADC |
Answer» (i) Consider △ ABC and △ ADC It is given that AB = AD and BC = DC AC is common i.e. AC = AC By SSS congruence criterion △ ABC ≅ △ ADC ……… (1) ∠ BAC = ∠ DAC (c. p. c. t) So we get ∠ BAE = ∠ DAE We know that AC bisects the ∠ BAD i.e. ∠ A So we get ∠ BCA = ∠ DCA (c. p. c. t) It can be written as ∠ BCE = ∠ DCE So we know that AC bisects ∠ BCD i.e. ∠ C (ii) Consider △ ABE and △ ADE It is given that AB = AD AE is common i.e. AE = AE By SAS congruence criterion △ ABE ≅ ∠ ADE BE = DE (c. p. c. t) (iii) We know that △ ABC ≅ △ ADC Therefore, by c. p. c. t ∠ ABC = ∠ ADC |
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