1. Module 7. 2 – Isosceles and Equilateral Triangles
Module 7.2 – Isosceles and Equilateral Triangles Today you will need your: Notes Textbook

2. Isosceles Triangle
Isosceles Triangles are triangles with AT LEAST two congruent sides.
Legs of an isosceles triangle are the two congruent sides.
Base of an isosceles triangle is the non-congruent side.
Leg
Leg
Base

3. Isosceles Triangle
Base
Leg
Base
Leg
Leg
Leg

4. Base Angles of Isosceles triangles are ALWAYS CONGRUENT!!
Isosceles Triangle - Angles
Isosceles Triangles are triangles with AT LEAST two congruent sides.
Vertex Angle – always across from the base
Base Angles – always across from the congruent sides.
Base Angles of Isosceles triangles are ALWAYS CONGRUENT!!
Vertex Angle
Base Angle
Base Angle

5. Isosceles Right Triangle
What must the measures of the base angles of an isosceles right triangle be?
45°
90°/2 =
45°
Base = Hypotenuse
Leg
45°
Leg

6. Isosceles Triangle – Solving for Angles and Sides
Determine the value of the missing angles.
62°

7. Isosceles Triangle – Solving for Angles and Sides
Determine the value of ‘x’ and use that value to find ALL angle measures.
(9x + 20)°
(7x + 30)°

8. Isosceles Triangle – Solving for Angles and Sides
Determine the value of ‘x’ and use that value to find ALL angle measures.
(10x)°
(x + 48)°

9. Isosceles Triangle – Solving for Angles and Sides
Determine the value of ‘x’ and use that value to find all possible side measures.
8x - 12
4x + 20

10. Isosceles Triangle – Solving for Angles and Sides
Determine the value of ‘x’ and use that value to find all possible side measures. 4x
10x - 23
3x + 5

11. Equilateral Triangle
Equilateral Triangles are triangles with ALL sides congruent.

12. Equilateral Triangle
Equilateral Triangles must also have all three ANGLES congruent.

13. Equilateral Triangle = Equiangular Triangle
Equiangular Triangle - a triangle where all ANGLES are congruent.
What must the interior angle measures of an equilateral/equiangular triangle be?
60°
180°/3 =
60°
60°
60°

14. Equilateral Triangle
Equilateral Triangles are also a special type of what kind of triangle?
Isosceles!

15. Equilateral Triangle – Solving for Angles and Sides
Determine the value of ‘x’ and use that value to find ALL angle measures.
(12x)°

16. Isosceles Triangle – Solving for Angles and Sides
Determine the value of ‘x’ and use that value to find all possible side measures.
8x - 20
3x + 15

17. Isosceles Triangle – Solving for Angles and Sides
Determine the value of ‘x’, ‘y’, and all possible side measures.
10x
7x + 12 2y

18. Classwork/Homework
Pages – all problems