Warm Up-9/17/09 #3 • Find the coordinate of the midpoint of AB if the coordinate of A is 7 and the coordinate of B is 201. Draw a diagram for credit!
1.4 Angles Obj: Use AAP and the definition of angle bisector to find angle measures.
Angle • Formed by two rays or segments with the same endpoint E Side F
• Notation:
Side
G
Vertex
Naming an Angle: • 1. Use three points E
– Vertex must be the middle
• 2. Use vertex
Side F
1 Side
• 3. Use a number
G
Vertex
Example 1 • Name each angle in every way possible. A C
1 B
2
D
Classifying Angles • Acute – measure between 0 and 90
• Right – measure of 90
• Obtuse – Measure between 90 and 180
• Straight – measure of 180 Angle
Adjacent Angles • Angles with a common vertex and a common side, but no common interior points • Adjacent
Angle Addition Postulate AAP •m∠AOB + m∠BOC = m∠AOC B C A
O
AND…. • m∠DOE + m∠EOF = 180 E
D
O
F
Congruent Angles • Two angles with equal measures • Notation: m∠1 = m∠2 • Or: ∠1 ≅ ∠2
1
• How to mark the diagram: • More than one pair of ≅ angles?
2
Angle Bisector • Ray or segment that divides an angle into two congruent adjacent angles
30° 30°
Example 2 • Segment AL bisects ∠KAT. Find x. • m∠1 = 7x +3 K • m∠2 = 6x + 7 L 2 3 1 T S A
Example 3 • m∠1 = x, m∠3 = 4x. Find x.
K L
S
3 A
2 1
T
Homework… • Pages 21-22 • 1-22, 26, 29, 31, 33 • Written Exercises