let d to be the distance:
7. A(2,3), B(6,3), C(2,7)
dᵃᵇ= √((2-6)²+(3-3)²)
dᵃᵇ= 4
dᵃc=√((2-2)²+(7-3)²)= 4
dᵇc=√((2-6)²+(7-3)²)=0
a²+b²=c²
4²+4²=32
so it is a right triangle.
9.
A(1,9), B(4,8), C(2,5)
d AB= √((8-4)²+(4-9)²)=√41
d BC=√((2-4)²+(5-8)²)=√13
d AC= √((2-1)²+(5-9)²)=√17
(√17)²+(√13)²=(√41)²
17+13=41
30≠41
so it is not a right triangle.
15.
Add the interior opposite angles together to get the exterior angle:
∠2 = 75+64= 139
17.
24+2x+8=3x+6
2x+32=3x+6
x+6=26
x=20
so the exterior angle is (3*20+6)=66
genius