Two angles are said to be adjacent when they share a common side and a vertex.
Vertically Opposite Angles - definition
Vertically opposite angles are the angles formed opposite to each other when two lines intersect.
Properties of Transversal - definition
A pair of parallel lines is intersected by a transversal. Following are the properties: 1. Vertically opposite angles are equal. 2. Corresponding angles are equal 3. The interior angles formed on the same side of the transversal are supplementary. 4. Alternate angles are equal.