1. 5/2/2019
Adding Angles
When you want to add angles, use the notation m1, meaning the measure of 1.
If you add m1 + m2, what is your result?
m1 + m2 = 58.
m1 + m2 = mADC also.
Therefore, mADC = 58.
Lesson 1-4: Angles

2. Angle Addition Postulate
5/2/2019
Angle Addition Postulate
Postulate:
The sum of the two smaller angles will always equal the measure of the larger angle.
Complete:
m  ____ + m  ____ = m  _____
MRK
KRW
MRW
Lesson 1-4: Angles

3. Example: Angle Addition
5/2/2019
Example: Angle Addition
K is interior to MRW, m  MRK = (3x), m KRW = (x + 6) and mMRW = 90º. Find mMRK.
First, draw it!
MRK + KRW = MRW
3x + x + 6 = 90
4x + 6 = 90
– 6 = –6
4x = 84
x = 21 3x
x+6
Are we done?
mMRK = 3x = 3•21 = 63º
Lesson 1-4: Angles