warm up
1.
1 2 3
2.
4
5
3.
Name 2 pair of alternate interior angles
<5 & <3
and
<4 & <1
What is the sum of m<1 + m<2 + m<3?
180°
If m<4 = 65° and m<5 = 50°, what is m<2?
65°
(Hint: make the parallel lines and transversal
longer so that they jump out at you.)
90°
50°
130°
50°
40°
40° 50°
90°
40°
4.
Find all the angle measures
Quiz #2
1.
1 2 3
2.
4
5
3.
Name 2 pair of alternate interior angles
<5 & <3
and
<4 & <1
What is the sum of m<1 + m<2 + m<3?
180°
If m<4 = 45° and m<5 = 50°, what is m<2?
85°
98°
45°
135°
45°
37°
37° 45°
98°
37°
4.
Find all the angle measures
BC = 8.5
AC = 8
x = 10
x = 10
x=6
x=8
BC = 25
x = 13
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Triangle Sum Theorem
&
Exterior Angle Theorem
Triangle Sum Theorem
The sum of the angle measures in a triangle
equal 180°
1
3
2
m<1 + m<2 + m<3 = 180°
Exterior Angle Theorem
(your new best friend)
The measure of an exterior angle in a
triangle is the sum of the measures of
the 2 remote interior angles
remote
interior
angles
exterior
angle
2
1
3
m<4 = m<1 + m<2
4
an example with numbers
find x & y
82°
x = 68°
30°
x
y
y = 112°
find all the angle measures
40x
30
10x
120°, 30°, 30°
Assignment
♥ Triangle Puzzle
♥ Triangle Sum and Exterior Angle
Theorems Worksheet