a pizza, no ma
how you slic
If we had a pair of right angles, they would add
up to 90º + 90º = 180º.
Our pair of mystery angles make up the same
total angle as a pair of right angles, so
aº + bº = 180º.
We know that you can always fit a pair of right angles on a
straight line, but what if we don’t have right angles?
What might this pair of mystery angles (a and b) from our
crime scene sketch add up to?
Angles on a straight line add up to 180º
Whether a half turn is made up of two quarter turns or
lots of different small turns, the total angle of a half turn
is always 180º.
This means that when the angle on a straight line is
divided up into smaller angles we can always be sure that
they add up to 180º.
lf a p
izza is ha
90º + 9º + 81º = 180º
14 Chapter 1