1) Write your homework in your agenda:
Geometry CW puzzle
2) Graph your Computation Challenge.
3) Take out a piece of paper. Put your
name on it.
4) Open to your CRCT Warm-Up page.
Here’s your Warm-up…
CRCT Geometry
Review
Let’s see what you can do
The word bisect means to cut into two
congruent halves
 What is the difference between a line,
a line segment and a ray?

Line extends in two directions without
end
 Line segment is part of a line that has
two endpoints
 Ray is part of a line that has one end
point

Copying an angle
Constructing parallel lines
Bisecting a line segment or
Constructing a perpendicular
bisector
Copying a line segment
Constructing perpendicular lines
Bisecting an angle
NOW YOU TRY:
Joel wants to bisect angle <FGH. What
comes first? Use a straightedge to draw a ray.
To bisect PQ, Maria began by swinging equal
arcs from P and Q above the line segment
and labeling the intersection X. What
should she do next?
Swing equal arcs from P and Q
below the line segment.
NOW YOU TRY:
Uri wants to draw a line through point P that
is parallel to KD. What is the first step Uri
should take? Use a straightedge to draw a ray
through point P that crosses KD.
A line segment has a length of 36 cm. If Lisa
bisects the segment, what is the length of
each segment? 18cm
A sofa is pushed across the floor of a living
room. Which type of transformation is this?
Translation
The hour hand of a clock from 7 to 8. Which
type of transformation is this?
Rotation
You look at yourself in the mirror. Which type
of transformation is this new image?
Reflection
Translation
Add the
translating
coordinate to
the
preimage’s
ordered pair.
FOR EXAMPLE:
Translate
(-2,-3)
K (3,-4) by
K’ (1,-7)
Reflection
Over x-axis:
multiply y by -1
Over y-axis:
multiply x by -1
Over origin:
multiply x AND y
by -1
FOR EXAMPLE:
Reflect K (3,-4) over the xaxis K’ (3,4)
Rotation
90o or 270o
X- and y-values
switch. Verify the
signs based on
quadrant.
180o
Move to opposite
quadrant.
X- and y-values stay
the same.
Verify the signs.
FOR EXAMPLE: Rotate
K (3,-4) 90o clockwise
K’ (-4,-3)
NOW YOU TRY:
Start: (-6,9) Reflect over y-axis
Finish: (6,9)
Start: (-4,-2) Translate (-3,10)
Finish: (-7,8)
Start: (-9,0) Rotate 270o counterclockwise
Finish: (0,9)
NOW YOU TRY:
y
B’
3
y
B
x
x
3
C’
–3
C
Reflect triangle ABC over the yaxis. What are the new
coordinates?
(0,0), (-2,3), (-2,-3)
Translate triangle ABC (-5,-3)
What are the new coordinates?
(-4,2), (0,2), (-4,-2)
Original x Scale Factor = Dilation
SF < 1 is a reduction
SF > 1 is an enlargement
If a percent of dilation is given, multiply
by the decimal version of the percent
4
5.6
4 x SF = 5.6
SF = 1.4
NOW YOU TRY:
Dilate (9,6) by a scale factor of 1/3 (3,2)
What is the scale factor for N(6,-2)
and its dilation of N’(15, -5)? SF = 5/2
A square in a coordinate plane
undergoes a 40% dilation. One
corner of the square originally had
coordinates (4,6). What are the
dilated coordinates? (1.6, 2.4)
The word corresponding means same
position in similar figures
The word congruent means exactly the
same size and shape
The word similar means same shape, but
different size. Sides are proportionate.
Scale factor = length ratio= perimeter
ratio
Scale factor2 = area ratio
NOW YOU TRY:
A rectangle has an area of 30 feet. A similar
rectangle has an area of 270 feet. What is
the scale factor? 3
What is the length of the missing side?
t = 150 cm
NOW YOU TRY: What is the scale factor, length ratio
and area ratio?
14 km
x
12 km
6 km
Scale Factor = ½, length ratio = ½, area
ratio = ¼
Rotations and translations of two
dimensional figures can be used to form
3D figures.




A circle rotating about a line through its
center makes a sphere
A triangle rotating about a vertical line makes
a cone
A square that has been translated makes a
rectangular prism
A circle that has been translated makes a
cylinder
Cross sections are views inside a 3D
object after it has been sliced
 Slices can be made horizontally,
vertically, or diagonally
Cross Sections of a Cylinder:
1)
Horizontal: circle
2)
Vertical: rectangle
3)
Diagonally: oval
NOW YOU TRY:
What 3D figure will be formed if rectangle
ABCD is rotated about AB?
cylinder
What 3D figure is formed when you translate a
circle?
cylinder
A rectangular prism is cut vertically, what is the
cross section? square
Suppose a cone is cut by a plane. Which of the
following cross sections is NOT possible?
Circle Ellipse
Square
Triangle
square