Question

verify experimentally that the sum of a pair of two co interior angle on the same side of a transversal which intersect the two parallel line is 180

Answer 1

See the Attachment.

The green line is the transversal. I have mentioned 4 angles in it.

According to the properties of the transversal,

Angle 1 = Angle 2 ........... (1)

Angle 3 = Angle 4 ...........(2)

Now the two co-interior angles are Angle 1 & Angle 4.

We have to show that their sum is 180.

We take

Angle 2 + Angle 4 = 180  ( Sum of angles on a straight line is always 180)

Angle 1 + Angle 4 = 180   ( by expression (1) )

Which is our required answer.

So  the sum of a pair of two co interior angle on the same side of a transversal which intersect the two parallel line is 180.