Warm-up: Solve for x and classify the triangle.

(5x + 2)

(6x + 5) (4x + 8)

(9x + 7) (4x + 8)

(9 – x)

How long must each side of the drawbridge be so that the bridge spans the river when both sides come down?

Can you form a triangle using any three lengths??

Investigate:Instructions:• Get a straw and a ruler• Pick a number 1-8• Cut the straw the length of the number you chose. (in

inches)• Please throw the extra away so you don’t get confused.• Now find 2 other people and try to make a triangle with

your straw. Record the combinations. Some combinations will work, others won’t. You need to fill up the entire graph with no repetitions of the same combination.

• When you are finished please throw the straw away, put the ruler back, and have a seat. We will discuss when everyone finishes and try to fill in the Triangle Sum Conjecture.

Triangle Inequality Conjecture

The sum of the lengths of any two sides of a triangle is __________the length of the third side.

Ex 1: Which of the following segments could form a triangle?

A. 6, 8, 10B. 3, 3, 3C. 2, 3, 5D. 8, 2, 9E. 10, 3, 4F. 1, 1, 2

EX 2: Find the range of possible side lengths for the third side of the triangle.

1. 6 and 11

2. 17 and 22

3. 78 and 111

Ex 3: Ordering Triangle Side Lengths and Angle Measures

Write the angles in order from smallest to largest.

Ex 4: Ordering Triangle Side Lengths and

Angle Measures

Write the sides in order from shortest to

longest.

EX 5: Solve for x.

120x

EX 6: Solve for x.

120

(x + 9)

(2x – 3)

EX 7:Find the missing angles.

5m

4m

3m

2m

1m

46

65

1

2

5

4

3

82

142