Given that,
ABCD is a cyclic quadrilateral in which
(i) Since,
EA = ED
Then,
∠EAD = ∠EDA ...(i)
(Opposite angles to equal sides)
Since,
ABCD is a cyclic quadrilateral
Then,
∠ABC + ∠ADC = 180°
But,
∠ABC + ∠EBC = 180°
(Linear pair)
Then,
∠ADC = ∠EBC ...(ii)
Compare (i) and (ii), we get
∠EAD = ∠EBC ...(iii)
Since,
corresponding angles are equal
Then,
BC ǁ AD
(ii) From (iii), we have
∠EAD = ∠EBC
Similarly,
∠EDA = ∠ECB .... (iv)
Compare equations (i), (iii) and (iv), we get
∠EBC = ∠ECB
EB = EC
(Opposite angles to equal sides)