Question

is it possible for two perpendicular lines to form only one right angle

Answer 1

yes

Answer 2

yes

Answer 3

if the lines extend infinitely in both directions, then no

Answer 4

why?

Answer 5

if one angle is 90, then the vertical angle paired with it is also 90

Answer 6

if x is the missing angle, then 90+x = 180 ----> x = 90

so this can be used to show all 4 angles are 90 degrees

Answer 7

a and b are rays or line segments in the ybarrap example. Therefore, this does not constitute a counter example to jim_thompson5910's conclusion.