1. Triangle Inequalities
Objective:
Discover the inequalities between sides and angles of a triangle

2. 1. Draw 3 segments on your paper CA = 3 cm
AT = 4 cm
CT = 8 cm
3. Draw 3 more segments on your paper DO = 3 cm
DG = 4 cm
OG = 7 cm
2. Construct or draw ∆CAT
4. Construct or draw ∆DOG
The sum of the lengths of any two sides of a triangle is _________ than the third side.
Triangle Inequality Conjecture
greater

3. 1. Draw a scalene triangle use a straightedgeM s L
Measure all angles and label:
L = largest angle
M = middle angle
S = Smallest angle l
3. Measure all sides and label: m
l = largest side
m = middle side
s = smallest side S
4. Any patterns?
In a triangle, if one side is longer than another, then the angle opposite the longer side is _________________
______________________
Side-Angle Inequality Conjecture
larger than the angle opposite the shorter side.

4. Triangle Exterior Angle Conjecture
1. Draw a scalene triangle use a straightedge
2. Extend one side beyond triangle
Exterior angle: an angle that forms a linear pair with an interior angle
Remote interior angles: two angles that do not share a vertex with an exterior angle
3. Measure exterior and remote interior angles.
Triangle Exterior Angle Conjecture
The measure of an exterior angle of a triangle ______________________________________________.
is equal to the sum of the remote interior angles

5. Examples Pg 216 #1-17, 19-22 List a, b, c from smallest to greatest.
Triangle or not?
8cm , 10 cm, 12 cm
4cm, 4cm, 8cm
C, B, A
Yes A
Pg 216 #1-17, 19-22 No B
550
Find x
800
720 C
1200 x
400