1. Equilateral, isosceles, right and Pythagorean theorem
By: Mya Conti

2. Key Words Equilateral Triangle: Having all it’s sides the same length.
Isosceles Triangle: Having at least 2 congruent sides.
Right Triangle: A triangle with a 90° angle.

3. Key Words
Pythagorean Theorem: In a right triangle, the square of the length of the hypotenuse is equal to the sum of the squared length of the legs.
*** c2=a2+b2 ***
a c b

4. Steps to Solve For a Right Triangle:
Ex 1: 9in 15 in c2=a2+b2 12 in 152= = =225 Yes, right triangle
1. Write out and fill in Pythagorean Theorem formula.
*remember c is always the longest side*
2. Solve the squared numbers on each side of the equation.
3. Add any that need to be added together.
4. If equal, right triangle!

5. State if Each Triangle is a Right Triangle:
Ex 2: 50.52= = = yes
Ex 3: 172= = ≠ 225 no
17 ft
12 ft
49.5 cm
50.5 cm
9 ft
10 cm

6. State if Each Triangle is a Right Triangle:
Practice 1: 112= 92 + √ = ≠196 no
Practice 2: 782= = =6084 yes
72 cm
78 cm
9 yd
11 yd
√115 yd
30 cm

7. Equilateral and Isosceles
Tic marks(l): Show the lengths of sides that are equal.
Equal angle marks: Show the degree of angles that are equal. ( ) ( ) (

8. Equilateral or Isosceles?
Problem 1: Isosceles
Problem 2: Isosceles ) ) ( (

9. Triangle Inequality
By: Mya Conti

10. Key Words < : Less than > : Greater than
Triangle Inequality Theorem:
The sum of the lengths of any 2 sides of a triangle is greater than the length of the 3rd side.
AB+BC>AC
AC+BC>AB
AB+AC>BC B A C

11. Steps:
When given two lengths subtract them for the left side of inequality
Then add them for the right side of the inequality
In between the two would be < x < since x, the third side has to be in the middle of those two new numbers
Ex 1: A < x < B

12. Describe the possible length of the third sides:
Ex 2: A triangle has one side of length 14 ft and another of 10 ft = =24 4 < x < 24
Ex 3: A triangle has one side of length 5 in and another of 6 in. 6-5=1 6+5=11 1 < x < 11

13. Describe the possible length of the third sides:
Practice 1: A triangle has one side length of 14 in and another of 21 in = =28 7 < x < 28
Practice 2: A triangle has one side length of 15.5 ft and another of 25 ft = = < x < 40.5