5.2 Angle Bisectors and
Perpendicular Lines
Angle Bisectors
• To bisect something is to
cut it into two equal parts
• The ray that divides the
angle is called an angle
bisector
• Measure angle ACB.
What degree is it?
• Measure angle ACD.
What degree is this?
• Measure angle DCB.
What is this degree?
• Does the line D bisect
angle ACB?
• If I bisect a right angle, what will the size of
each angle be?
• Bisect the following angles.
• An angle is bisected. Each resulting angle is
780. How big was the original angle?
• The size of one resulting angle after the
original angle is bisected is equal to the
supplement of the original angle. What is the
measure of the original angle?
• Using a protractor determine which of the
following lines are perpendicular.
• A crooked table leg makes an angle of 86.70
with the tabletop. How much must the
carpenter move the leg so that it is
perpendicular to the tabletop?
• At what approximate angle does the hill
incline from the horizontal?
• A carpenter is inlaying different types of wood
on a tabletop. What must be the size of
angles a, b, c, and d? (
(hint: remember that a straight line is how
many degrees? And the 3 angles of a triangle
always add to 180 degrees)
• Practice questions page 229
# 2, 4 and worksheet