The missing justification is for the statement that three angles add to a particular angle. The appropriate choice is ...
... c. Angle Addition Postulate
Answer:
a) 6/9 shaded.
b) About 67% is shaded. (66.6% repeating rounded to 67%)
It is in form
0=ax^2+bx+c
0=-3x^2-2x+6
a=-3
b=-2
c=6
so
x=
x=
x=
x=
x=
x=
x= or
