Explanation:
Given: A parallelogram ABCD with AC as its diagonal
To prove: <A=C & <B=<D
Proof:
Opposite sides of parallelogram is parallel
So, AB || DC and AD || BC.
Since AB || DC
& AC is the transversal
< BAC = < DCA (Alternate angles...(1) )
Since AD || BC & AC is the transversal
<DAC = < BCA (Alternate angles)...(2)
when adding equation 1 and 2
<A=<C
In similar case,
<B=<D