Answer:

1.) When two lines intersect each other, then the pair of opposite angles formed at the vertex are called vertical angles

2.)Two angles with a common arm and vertex are called adjacent angles

3.)by listing their vertices in corresponding orders. In Figure , Δ BAT ≅ Δ ICE. Example 1: If Δ PQR ≅ Δ STU which parts must have equal measurements? These parts are equal because corresponding parts of congruent triangles are congruent.

4.) For example, angle 130° and angle 50° are supplementary angles because sum of 130° and 50° is equal to 180°. Ex: ∠A + ∠B = 180°.