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1.2.2: Bisecting Segments and Angles
Henri is designing a set for
the upcoming school play.
The play opens with the
main character in front of
the clock tower at 1:00 P.M.
Henri easily constructs the
hands of the clock for the
first scene, but needs help
with the placement of the
hands for the second
scene. The second scene
takes place 2 hours later in
front of the same tower.
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1.2.2: Bisecting Segments and Angles
1. Use a compass and a straightedge to construct the
hands of the clock for the second scene. Be sure to
use construction methods previously learned.
2. If the measure of the angle of the hands for the first
scene is 30˚, what is the measure of the angle of the
hands for the second scene?
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1.2.2: Bisecting Segments and Angles
1. Use a compass and a straightedge to construct the
hands of the clock for the second scene. Be sure to
use construction methods previously learned.
• Use the vertex of the original angle as the vertex
for the new angle of the clock hands.
• Copy the original angle, using the lower side of the
angle as the starting ray (the hour hand).
• Copy the original angle again to construct the
position for the second scene, with the ray
representing the hour hand at the 3:00 position.
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1.2.2: Bisecting Segments and Angles
The problem scenario
specified that the second
scene takes place 2 hours
later, so the original angle
ray representing the minute
hand should stay in place, at
the 12:00 position. The
second angle ray
representing the hour hand
is at 3:00. Therefore, the
angle that represents the
time of the second scene is
encompassed by the rays
pointing at 12:00 and 3:00.
1.2.2: Bisecting Segments and Angles
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2. If the measure of the angle of the hands for the first
scene is 30˚, what is the measure of the angle of the
hands for the second scene?
• The original position is 30˚.
• The second scene is 2 hours later, meaning the
angle opened an additional 60˚ (30 • 2 = 60).
• The resulting angle is 90˚ (30 + 60 = 90).
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1.2.2: Bisecting Segments and Angles