Answer:
Angle = A
A7 = A4 (Alternate interior angles)
A14 = A11 (Vertically opposite angles)
A11 = A6(Corresponding angles)
A4 = A14 (Given)
From this, we can get A6 = A4
A6 and A4 are alternate angles and are equal. So c and d are parallel.
A7 + A10 = 180 (Linear pair of angles) - ( 1 )
A13 = A10(Alternate interior angles)
Putting A13 in place of A10 in ( 1 ),
A7 + A13 = 180
Hence proved
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