Download Interior Triangle Angle Measures The measures of the interior

February 13, 2017
Interior Triangle Angle Measures
The measures of the interior angles in a triangle add up to _____.
55
90
x
What is the measure of angle x? ___________
Try It pg. 354
February 13, 2017
We can take a regular triangle and extend one of the sides to form
a 4th angle.
This angle is called an exterior angle.
An exterior angle of a triangle is an angled formed by a side and an
______________________ of an adjacent side.
2
4
1
3
The 2 angles that are not adjacent to the exterior angle are
known as the ___________________________ angles.
What do we know about the sum of angles 1, 2, and 3?
What do we know about the sum of angles 1 and 4?
Therefore, we can say that the measure of an exterior angle of a
triangle is equal to the sum of the measures of its ___________
_________________________________
February 13, 2017
2
4
1
3
If angle 2 = 38° and angle 1 = 70°, what is the measure of angle 4?
Sometimes we can use algebra to find angle measures.
2
(8x+21)°
(25x+19)°
4
1
(16x)°
3
What is the measure of angle 1?
Step 1: Solve for x.
Step 2: Plug in x to find the measure of angle 1.
Try It pg. 355
pg. 356