There is a theorem in parallelogram where opposite angles are equal, prove it.
According to the question,
In a parallelogram, opposite angles are equal.
Given: Parallelogram
To prove: and
Proof :
In parallelogram
Consider,
and is transversal
[interior Angles on the same side of transversal]… (i)
Now, consider and transversal
[interior Angles on the same side of transversal]… (ii)
From (i) and (ii) we get ;
Similarly,
Hence, it is proved that opposite angles of a parallelogram are equal