Name ___________________________________ Per._____ Date ______________
CC Geometry
Day 1
Triangle Proof CW
Welcome to Analytic Geometric Proofs ...YAY!
Follow the 6-step format each time you do an analytic/coordinate proof.
Properties (Used for Step 2)
If a triangle has 3 equal sides, then it is an equilateral triangle.
If a triangle has 2 equal sides, then it is an isosceles triangle.
If a triangle has 0 equal sides, then it is scalene.
If a triangle contains a right angle, then it is a right triangle.
If a triangle contains a right angle AND has 2 equal sides, then it is an isosceles right triangle.
Let’s try a few 
1. Given:
Prove:
Δ ABC with A (5, 7), B (2, 3), and C (1, 4)
Δ ABC is isosceles
2. Given:
Prove:
Δ ABC with A (-3, 6), B (-9, 0), and C (9, 0)
Δ ABC is scalene
3. Given:
Δ ABC with A (0, 0), B (2, 3), and C (4, 0)
Prove:
What type of triangle is Δ ABC.
Name___________________________Per___Date____________
CC Geometry
Day 1
Triangle Proof HW
Prove the following triangles using a 6-step proof.
1. Given:
Prove:
Δ ABC with A (10, 3), B (-2, 3), and C (4, 1)
Δ ABC is isosceles
2. Given:
Prove:
Δ EFG with E (-3, 3), F (-2, -1), and G (2, 1)
Δ EFG is scalene