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Angle Bisectors. Brett Solberg - AHS ‘11-’12. Warm-up. Solve for x if B is the midpoint. Solve for x Complimentary is how many degrees? Supplementary is how many degrees? Get out your homework and your notes. What problems do we need to review?. Announcements. Test/Review
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Angle Bisectors Brett Solberg - AHS ‘11-’12
Warm-up • Solve for x if B is the midpoint. • Solve for x • Complimentary is how many degrees? • Supplementary is how many degrees? • Get out your homework and your notes. • What problems do we need to review?
Announcements • Test/Review • Late Work/Missing Quiz • Definition Extra Credit • Books
Today’s Agenda • Angle Bisectors • Identification • Solving for variables
Review • Midpoint – point that bisects a line segment.
Midpoint Problems • B is the midpoint of AC. Solve for x. • B is the midpoint of AC. If AC = 50, solve for x.
Angle Bisectors • A ray that divides a an angle into 2 congruent angles. • BD bisects ∠ABC • ∠ABD ≅ ∠DBC
Examples • Ray BD bisects ∠ABC. • What is the measure of ∠ABD and ∠DBC
Example 1 • ∠DBC = 3x + 5 • ∠ABD = 4x + 2 • m∠DBC= ? • m∠ABD= ?
Example 2 • BE bisects ∠ABD • ∠ABE = 2x + 1 • ∠EBD = 4x – 7 • Find m∠EBD (fix)
Angle Addition Postulate • m∠ABD + m∠DBC = m∠ABC
Example 3 • Ray BD bisects ∠ABC • ∠ABD = 2x • ∠ABC = 3x + 5 • m∠ABC = ?