Linear pair of angles
Linear pair of angles are formed when two lines intersect each other at a single point.
The angles need to be adjacent to be linear.
The image shows two lines that intersect and form angles a,b,c, and d.
We need to check the angles that are adjacent. If angles are opposed (also called vertical) they don't qualify as linear pairs.
These angles are linear:
a and c
b and c
b and d
a and d
Linear pairs always add up to 180°.
Let's check all that apply:
since a and b are not linear pairs, they don't add up to 180°.
Angles a and c are linear, this must be checked
Note: Some of the answers are true, but they don't correspond to the definition of linear pairs, like a and b being congruent