Interior angle of same side of transversal are

- Between lines i.e interior
- On the same side of transversal, i.e, either on left or on right

∠3 & ∠5 are interior angles on same side of transversal

∠4 & ∠6 are interior angles on same side of transversal

For parallel lines,

Interior angles on same side of transversal are supplementary

∠3 + ∠5 = 180°

∠4 + ∠6 = 180°