Guide
Leo argues that the measure of an exterior angle of a triangle is
equal to the sum of the measures of the two remote interior angles of
the triangle. He uses the diagram shown in his argument.
Xº
Leo writes the steps listed.
Step 1.r+x=180, since the sum of the measures of supplementary
angles is 180°
Step 2. p+q+r=180, since the sum of the measures of the angles
of any triangle is 180°
Which equations follow from step 1 and step 2 that Leo could use to
complete his argument?
r+x=p+q+r
r+x-r=p+q+r-r
x=p+q
p+q+r=180
bp+q+r-r=180-r
p+q=180-r
x+r=p+q+r
x+r-r=p+q+r+r
x=p+q+2r
(r+x) + (p+q+r)=180+180
2r+x+p+q=360