Let's say you opened your laptop and positioned the
screen so it's exactly at 90° - a right angle - from your
keyboard. now, let's say you could take the screen and
push it all the way down beyond 90°, until the back of the
screen is flat against your desk. it looks as if the angle
disappeared but hasn't. what is the angle called, and
what is the measurement?
a. straight angle at 180°
b. linear angle at 90°
c. collinear angle at 120°
d. horizontal angle at 180°