Focus......Use a variety of methods to construct perpendicular bisectors of Line segments
Bisect means to cut in half. When you bisect a line....you cut it in half.
If you construct the bisector at right angles (90 degrees) to the line segment.....you've constructed a Perpendicular Bisector.
There are several ways to construct perpendicular bisectors:
a) Use paper folding.
b) Use a compass.
c) Use a mira.
d) Use a ruler.
Method 1 - Paper Folding
1. Draw a line segment AB (about 10cm)
2. Fold the line in half so that Point B
is on top of point A.
3. Draw a line down the crease in your paper. This is your perpendicular bisector.
Method #2 - Mira
1. Draw a line segment AB (10cm)
2. Place the mira in the middle of the line segment, the reflection of Point A should be on top of Point B (otherwise your line won't be straight).
3. Draw a line down the mira
Method #3 - Use a Compass...
Method #4 - Ruler
1.) Draw a line segment AB (10 cm)
2.) Place the ruler on a diagonal
so that A is on one side of the ruler and
B is on the other side.
3.) Draw a line segment down each side of the ruler.
4.) Turn the ruler so that A and B are on opposite sides of the ruler and draw line segments again.
5.) Label the points where the line segments meet,
Point "C" and Point "D".
6.) Connect C and D to create a new line segment. CD is perpendicular to AB.
Homework:
pg. 308-309
# 1-7
When you divide an Angle into two equal parts....
you bisect the angle.
There are several ways to bisect an angle:
• Paper Folding
• Using a mira
• Use a compass.
• Use a protractor.
• Ask a math teacher to do it for you.
• Use a triangle and a ruler.
Protractor:
Q. How can you use your protractor to
check your work?
- make sure the two angles you have created are the same
- make sure the two angles add up to the measurement of the original angle
Practice:
Page 312 and 313....3,4,5,6,and 7
You must use your protractor to construct the angles!
