Question

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

Answer 1

See below

Explanation:

In a parallelogram , the opposite angles are equal.

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