Answer:
∴Given Δ ABC is not a right-angle triangle
a= AB = √45 = 3√5
b = BC = 12
c = AC = √45 = 3√5
Explanation:
Given vertices are A(3,3) and B(6,9)

AB =

Given vertices are B(6,9) and C( 6,-3)
=

BC = 12
Given vertices are A(3,3) and C( 6,-3)

AC² = AB²+BC²
45 = 45+144
45 ≠ 189
∴Given Δ ABC is not a right angle triangle