ABCD is aparallegram. The circle through A,B and C intersects CD produced at E. If AB=10cm, BC= 8cm, CE=14cm. find AE

given: ABCD is a parallelogram. A circle through A, B and C intersects CD produced at E.

AB=10cm, BC= 8cm, CE=14cm. 

to find AE

∠AED+∠ABC=180 deg ..........(1)  [sum of opposite angles of the concyclic quadrilateral is supplementary]

∠EDA+∠ADC=180 deg ..........(2)  [angles formed on the same side of  a straight line]

∠EDA+∠ABC=180 deg............(3) [since ∠ADC=∠ABC opposite angles of a parallelogram are equal]

from (1) and (3)

∠AED+∠ABC=∠EDA+∠ABC

∠AED=∠EDA  ................(4)

now in the triangle AED,

from (4) AE=AD [sides opposite to equal angles are equal ]

hence AE=AD=BC=8 cm [AD=BC opposite sides of a parallelogram are equal]

hope this helps you.

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Given: ABCD is a parallelogram. A circle through A, B, C intersects CD produced at E.
To prove: AE = AD
Proof:
∠AED + ∠ABC = 180� ... (1) (Sum of opposite angles of cyclic quadrilaterals is 180�)
∠ADE + ∠ADC = 180� ... (2) (linear pair)
∠ABC = ∠ADC ... (3) (opposite angles of parallelogram are equal)
From (1) and (2)
∠AED + ∠ABC = ∠ADE + ∠ADC
⇒∠AED = ∠ADE (using (3))
In ∆AED,
∠AED = ∠ADE
⇒AD = AE (equal sides have equal angles opposite to them)
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