Bisects

• x=67
• x=43
• x=55
• x=12

It divides or bisects a segment into two congruent segments; the point in the middle of the segment.

• point

• midpoint

• line

• bisector

• m<EFJ = 90, m<JFG = 90

• m<EFJ = 45 m<JFG = 45

• m<EFJ = 180, m<JFG = 180

• m<EFJ = 45 m<JFG = 90

What is the value of x?

• 10.667

• 11.333

• 42

• 10

What does it mean to bisect a segment or an angle?

• Split it into 3 equal parts.

• Split it into 2 equal parts.

• Split into 4 equal parts.

• Double it.

Given: m∠LAN = 30⁰ , m∠1 = 15⁰
Prove: AM bisects ∠LAN
Step 1: m∠LAN = 30⁰ 
Step 2: m∠1 + m∠2 = m∠LAN
Step 3: m∠1 + m∠2 = 30⁰
Step 4: m∠1 = 15⁰
What is the justification for Step 4?

• Given

• Substitution

• Angle addition postulate

• Definition of congruent angles

Given: m∠LAN = 30⁰ , m∠1 = 15⁰
Prove: AM bisects ∠LAN
Step 1: m∠LAN = 30⁰ 
Step 2: m∠1 + m∠2 = m∠LAN
Step 3: m∠1 + m∠2 = 30⁰
Step 4: m∠1 = 15⁰
Step 5: 15⁰ + m∠2 = 30⁰
Step 6: m∠2 = 15⁰
What is the justification for Step 6?

• Subtraction property of equality

• Substitution

• Addition property of equality

• Definition of congruent angles

Given: m∠LAN = 30⁰ , m∠1 = 15⁰
Prove: AM bisects ∠LAN
Step 1: m∠LAN = 30⁰ 
Step 2: m∠1 + m∠2 = m∠LAN
Step 3: m∠1 + m∠2 = 30⁰
Step 4: m∠1 = 15⁰
Step 5: 15⁰ + m∠2 = 30⁰
Step 6: m∠2 = 15⁰
Step 7: m∠1 = m∠2
What is the justification for Step 7?

• Subtraction property of equality

• Transitive property of equality

• Addition property of equality

• Definition of congruent angles

What is the missing statement in the proof?

• 2m∠ABD=m∠ABD+m∠ABD

• m∠ABD=m∠DBC

• m∠ABC=m∠ABC

• m∠ABD+m∠ABD=m∠ABD+m∠DBC

• def. of midpoint

• def. of linear pair

• AAP (angle addition postulate)

• def. of angle bisector