1. Exterior Angle TheoremExterior Angle Theorem
You will learn to identify exterior angles and remote interior
angles of a triangle and use the Exterior Angle Theorem.
1) Interior angle
2) Exterior angle
3) Remote interior angle

2. Exterior Angle TheoremExterior Angle Theorem
1
2 3 4
P
Q R
interior
Angle 4 is called an _______ angle of ΔPQR.exterior
An exterior angle of a triangle is an angle that forms a _________ with one of
the angles of the triangle.
linear pair
____________________ of a triangle are the two angles that do not form
a linear pair with the exterior angle.
Remote interior angles

3. Exterior Angle TheoremExterior Angle Theorem
1
2
3 4 5
In the figure below, ∠ 2 and ∠ 3 are remote interior angles with respect to
what angle? ∠ 5

4. Exterior Angle TheoremExterior Angle Theorem
Theorem 7 – 3
Exterior
Angle
Theorem
The measure of an exterior angle of a triangle is equal to sum
of the measures of its ___________________.remote interior angles
X
432
1
ZY
m ∠ 4 =m ∠ 1 + m ∠ 2

5. Exterior Angle TheoremExterior Angle Theorem

6. Exterior Angle TheoremExterior Angle Theorem
Theorem 7 – 4
Exterior
Angle
Inequality
Theorem
The measure of an exterior angle of a triangle is greater than
the measures of either of its two ____________________.remote interior angles
X
432
1
ZY
m ∠ 4 > m ∠ 1
m ∠ 4 > m ∠ 2

7. Exterior Angle TheoremExterior Angle Theorem
∠ 1 and ∠ 3
74°
1 3
2
Name two angles in the triangle below that have measures less than 74°.
Theorem 7 – 5
If a triangle has one right angle, then the other two angles
must be _____.acute

8. Exterior Angle TheoremExterior Angle Theorem
3and1 ∠∠

9. Exterior Angle TheoremExterior Angle Theorem
The feather–shaped leaf is called a pinnatifid.
In the figure, does x = y? Explain.
x = y
?
__ + 81 = 32 + 7828
28°
109 = 110
No! x does not equal y

10. Exterior Angle TheoremExterior Angle Theorem
The feather–shaped leaf is called a pinnatifid.
In the figure, does x = y? Explain.
x = y
?
__ + 81 = 32 + 7828
28°
109 = 110
No! x does not equal y