Geometry (1)

Problem:



Solution:

21.) Collinear means on the same line, so both of these can be solutions

PRT
QRS

22.)  Name two linear pairs

The term linear pair is not very standard. I looked up the definition here.
http://www.icoachmath.com/math_dictionary/linear_pair.html

It said:
Linear Pair is a pair of adjacent angles that form a straight line.

So there is one linear pair the I can name
Angle PRS and angle SRT