1. I can write and solve equations to find unknown angle measures.

2. Angle A figure formed by two rays with a common endpoint or vertex.
The symbol ∠ means angle.
When an m is placed in front it means “the measure of the angle”

3. Angle Measure Sums
If the sum of two angle measures is 90°, the angles are complementary.
If the sum of two angle measures is 180°, the angles are supplementary.

4. Adjacent Angles
Share a vertex and a side but have no interior points in common.
Ex:
Angles 1 and 2 are adjacent.

5. Finding Supplements and Complements
The Leaning Tower of Pisa
Find each angle measure
We know a straight line measures 180°
3x – 35 and 2x must be supplements
So 3x – x = 180
x = 43
Substitute and the measures are
3(43) – 35 and 2(43)
94° and 86°

6. You try! Complementary means the sum is 90°
m∠A + m∠B = and m∠A = 5(m ∠B)
5(m ∠B) + m ∠B = 90
6(m ∠B) = 90
m ∠B = 15°

7. 6.1 Continued

8. Vertical Angles
Formed by two intersecting lines and are opposite each other.
Vertical angles have equal measure.
Angles with equal measure are congruent angles.
EX:
Angles 1 and 2 are vertical angles

9. Practice Find m∠2, m∠3, and m∠4 if we know that m∠1 = 25.7°

10. Try this!

11. Assignment
All
P.218 #7-19