How do you prove that 2 angles are equal in a parallelogram?

1 Answer
Chirag Mehta
Mar 1, 2018

See below

Explanation:

In a parallelogram , the opposite angles are equal.

wikipedia

So as you can see parallelogram has opposite sides parallel. So adjacent angles must sum up to 180°(because if the angle is more or less the lines would converge on either side)

Let ABCD be ||gm (||gm means parallelogram, it is a short notation)
#angleA+angle B=180°#

#angle B+angle C=180°#

Using elimination, substitution or whatever

#angleA-angle C=0°#

#angle A=angle C#
Hence proved

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