Constructing 2D Shapes

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Grade 6 Geometry Unit
Re-cap
 Given two of the three angles in a triangle, how could
we find the third angle?
 Given SAS how could we construct a triangle?
 Do you think we could construct a triangle give side
side side (SSS)?
 Do you think we could construct a triangle given angle
side angle (ASA)?
Constructing Triangles with SSS
 Goal: to construct triangle ABC with sides AB=6cm,
AC=5cm, and BC is equal to 4cm
6cm
 Step 1: Draw line AB which is 6cm long A
B
 Step 2: Set the compass so the pencil and the compass
point are 5cm apart
 Step 3: Place the
Compass on point A
and draw an arc
5cm
Constructing Triangles with SSS
 Step 4: Now, set the compass and pencil so that they are
4cm apart.
 Step 5: Place the compass point on B and draw an arc so the
lines insert. The point where the arcs insert, label it C
 Step 6: Draw segments AC and BC to complete the triangle,
and label each segments with its length
Constructing Triangles with AAA
 Goal: Draw a triangle that has the following degrees:




<A 100 degrees, < B45 degrees and <C 35 degrees
Step 1: Draw a tentative baseline (this means you will
probably erase some of the line after all your angles are
drawn)
Step 2:Label the first point with A A
Step 3: At point A, measure 100 degrees with your
protractor, make a dot at 100 degrees and mark your
dot with B
B
Step 4: Connect points A and point B
A
Constructing Triangles with AAA
 Step 5: From point B, measure 45 degrees with your
protractor, and mark that point with a dot and label it
C, connect B and C
 Connect point A and C to form your triangle
Constructing a Parallelogram
 Goal: To construct a parallelogram BACD where
AD=BC=5cm, BA=DC=2cm, Angle ABC=120 degrees,
and angle BDC=60 degrees
 Step 1: Use a ruler to draw a line segment that is 5cm
long B
5cm
C HINT: Since BC is 5cm, what’s AC?
 Step 2: At point B, measure and mark 120 degrees.
Draw segment BA 2cm long in the direction of 120
degrees.
2cm
120 degrees
5cm
Constructing a Parallelogram
 Step 3: Use a protractor to measure 60 degrees at point
C, and draw a line segment that is 2cm long
A
C
120 degrees
B
60 degrees
D
Step 4: Draw line segment AD to complete the
parallelogram
5cm
A
C
2cm
2cm
B
D
Task...
 A triangle where...
- PQ=6cm, QR=8cm, PR=10cm
- All sides of
CDE are 65mm
HFG=50 degrees, =60 degrees,
=70 degree
• A quadrilateral where...
- <C=110 degrees, <D=130 degrees, <F=50 degrees

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