Answer:
- base angles of an isosceles triangle
- angles at successive corners of any regular polygon
- angles either side of an angle bisector
- angles made by a perpendicular to a line (excluding vertical angles)
Explanation:
When it comes to angles, the term "adjacent" means different things in different contexts. Any pair of angles in a triangle are considered to be adjacent. The base angles of an isosceles triangle are adjacent congruent angles.
Angles at successive corners of any regular polygon are congruent adjacent angles.
Angle that have a common vertex and a common side are also called adjacent angles. Angles on either side of an angle bisector are adjacent congruent angles. Likewise any non-vertical pair of angles where lines cross at right angles are adjacent congruent angles.