270 likes | 445 Views
Lesson 4.3 Angle Bisectors pp. 129-134. Objectives: 1. To identify and apply the Angle Addition Postulate. 2. To define and apply angle bisectors. 3. To define and identify perpendicular lines. Definition.
E N D
Lesson 4.3 Angle Bisectors pp. 129-134
Objectives: 1. To identify and apply the Angle Addition Postulate. 2. To define and apply angle bisectors. 3. To define and identify perpendicular lines.
Definition Adjacent angles are two coplanar angles that have a common side and common vertex but no common interior points.
B D A C DAB and DAC are called adjacent angles.
B D A C BAC and DAC are NOT adjacent angles.
B C A E D BAC and CDE are NOT adjacent angles.
Postulate 4.3 Angle Addition Postulate. If K lies in the interior of MNP, then mMNP = mMNK + mKNP.
X T Z Y Example 1 Find mXYZ if mXYT = 25° and mTYZ = 15°. mXYZ =mXYT + mTYZ mXYZ = 25 + 15 mXYZ = 40°
C D A B Example 2 Find mDBC if mABC = 90° and mABD = 70°. mABC =mABD + mDBC 90 = 70 + mDBC 20° = mDBC
B D A C Find mBAC if mBAD = 35 and mDAC = 15.
Given mARQ = 30°, mARV = 70°, and mQRJ = 5°. If Q is in the interior of ARV, find mQRV.
Given mARQ = 30°, mARV = 70°, and mQRJ = 5°. If Q is in the interior of ARV, find mQRV. A 30° 70° R 40° Q V
Given mARQ = 30°, mARV = 70°, and mQRJ = 5°. If Q is in the exterior of ARV, find mQRV.
Given mARQ = 30°, mARV = 70°, and mQRJ = 5°. If Q is in the exterior of ARV, find mQRV. V A 100° 70° Q 30° R
Definition Anangle bisector is a ray that (except for its origin) is in the interior of an angle and forms congruent adjacent angles.
Definition Perpendicular lines are lines that intersect to form right angles. The symbol for perpendicular is .
Homework pp. 133-134
V W U Z Y X ►A. Exercises 11. Find mUYX if mUYW = 75° and mWYX = 35°.
V W U Z Y X ►B. Exercises 13. Find mUYV if mUYW = 85° and mVYW = 15°.
►B. Exercises 15. If FD is the bisector of EFC, what is true about 1 and 5? E D 1 C 5 F 2 4 3 A B
►B. Exercises 17. If FC bisects DFB and mDFB = 92°, what is m5? E D 1 C 5 F 2 4 3 A B
■ Cumulative Review In each problem, identify the sets into which the first figure divides the second. Justify your answer with a postulate or theorem. 26. plane, space
■ Cumulative Review In each problem, identify the sets into which the first figure divides the second. Justify your answer with a postulate or theorem. 27. point, line
■ Cumulative Review In each problem, identify the sets into which the first figure divides the second. Justify your answer with a postulate or theorem. 28. polygon, plane
■ Cumulative Review In each problem, identify the sets into which the first figure divides the second. Justify your answer with a postulate or theorem. 29. line, plane
■ Cumulative Review In each problem, identify the sets into which the first figure divides the second. Justify your answer with a postulate or theorem. 30. polyhedron, space