In figure, ABCD is a square and ∠DEC is an equilateral triangle. Prove that
(i) ∆ADE ≅ ∆BCE
(ii) AE = BE
(iii) ∠DAE = 15°
Given: AB = BC, AD = EC
To Prove: ∆ABE ≅ ∆CBD
Proof: In ∆ABC,
∵ AB = BC | Given
∴ ∠BAC = ∠BCA ...(1)
| Angles opposite to equal sides of a triangle are equal
AD = EC | Given
⇒ AD + DE = EC + DE
⇒ AE = CD ...(2)
Now, in ∆ABE and ∆CBD,
AE = CD | From (2)
AB = CB | Given
∠BAE = ∠BCD | From (1)
∴ ∆ABE ≅ ∆CBD | SAS congruence rule.