# how to use geolegs by thebest11

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```									 GeoLeg™                                       Protractor/Compass
Measure and Draw

Four-In-One geometry tool for
teachers and students

Raise Test Scores
Target Geometry and
Measurement

www.geoleg.com                                888-595-5347
INVESTIGATING CIRCLES
USE GEOLEGS OVER WHITE SURFACES OR ON OVERHEAD.

–– Circle

–– Blue Sleeve

–– Red Leg                 Open GeoLeg by rotating red
leg clockwise

0

• Discover relationships of angles to circles.
• Draw a circle on grid paper and count number of square grids that form the area.
• Compare the squares counted to the area found with A = πr2.
• Measure the length of the circumference of the circle.
• Compare the area to circumference.
• Draw a square around the circle and count the area out of the circle.
• Find factors of 360º to use for designing circle art.
• Express data through circle graphs.
FINDING AND MEASURING ANGLES
BLUE LINE IS SET ON 0º AND 180º. RED LINE GIVES ANGLE MEASURE.
Intersecting lines form four angles with special
relationships.

Vertical angles are congruent,    Supplementary angles are
opposite and reflective.     adjacent and have a sum of 180º.
60 + 120 + 60 + 120 = 360               60 + 120 = 180

Classify angles
Obtuse angle/arc                       by their
90º < B < 180º                      measures.

Acute angle/arc
0º < A < 90º                                           Complementary angles
have a sum of 90º.
∠x = 30
∠y = 90-30 = 60
Straight angle D = 180º
Semicircle = 180º
Circle = 360º
Tangent forms a right
Right angle C = 90º
Arc = 90º

Parallel Lines
∠1 = ∠1
∠2 = ∠2
∠1 + ∠2 = 180º
∠1 + ∠2 + ∠1 + ∠2 = 360º
MEASURE LENGTHS
USE GEOLEGS OVER WHITE SURFACE OR ON OVERHEAD.

Measure from Center
This pencil is 10cm long.

10 cm                              7 cm
+
This pencil is 17cm long.

Combine Lengths

Total length is 34 cm
BUILD POLYGONS BY
SLIDING THREE OR MORE
GEOLEGS TOGETHER.

Round angle measures
to nearest 5º.
Build a Triangle
1. Turn 3 GeoLegs right side up.
2. Open GeoLegs by rotating red leg clockwise.
3. Slide GeoLegs together leg to sleeve.
4. Choose one length and set it. Hold length in place and choose another.
5. To increase or decrease an angle measure, increase or decrease the
length of the opposite side.
6. Round angle measures to the nearest 5º.
7. For length of side, add blue seven to red length.
8. Round lengths to the nearest .5cm.

Isosceles Right Triangle
Round angle               Relationships seen:
45º                         measures                Sum of interior angles 90 + 45 + 45 + = 180º
to nearest 5º.            Sum of exterior angles 90 + 135 + 135 = 360º
7cm + 4cm = 11cm

7c

Perimeter               11 + 11 + 15.5 = 37.5cm
m
+
8.

Longest side opposite largest angle.
5c

45º
m

(hypotenuse and right angle)
=
15

Same number of congruent sides and angles (2)
.5
cm

One line of symmetry. (formed by congruent legs)
Pythagorean Theorem            112 + 112 = 15.52
90º               45º                             (a + b = c )
2   2    2

90º                                   45º          90º – 45º – 45º Theorem        15.5 = 11√2
(hypotenuse = leg √2)
7cm + 4cm = 11cm

10cm
Parallelogram
Relationships seen:
Opposite sides are congruent
Opposite angles are congruent
60º
11cm              120º
Opposite sides are parallel
supplementary
11cm
Diagonals bisect each other                                                          120º
Sum of interior angles                                                  60º
120 + 60 + 120 + 60 = 360
Sum of exterior angles
60 + 120 + 60 + 120 = 360
10cm
USE GEOLEG TO DRAW AND CONSTRUCT
• USE SHARP OR MECHANICAL PENCILS.
• WORK ON FLAT SURFACE
• USE MASKING TAPE IF PAPER SLIPS
18
0            15 30 45 60
75

16
5
L

15

90
0

105 120 135 150
135 120 105 9

GEO
EG
hinge

0

16
75

5
0
60
45 30 15

3 CM
legs

4
5

4
3247
: 57
6

CM
endpoints

TENT

7
US PA
7
8
9
10
GeoLeg is a better compass

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Old                                                                                                                       New

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1. Draw angles using GeoLeg.
a. Open GeoLeg to desired measure.
b. Mark vertex and points on each leg.
c. Connect points.

45º

2. Draw square (or any regular polygon)
m

3c
3c

90º
m

a. Know interior angle measures (90º).
b. Open GeoLeg to 90º.
c. Mark first vertex and 3cm points on each leg.
d. Connect points.
e. Measure and mark last 90º angle with 3cm legs.
f. Connect points to draw a square.
3. Circles can be drawn using GeoLeg center as a pivot
point.
Use drawing points on the leg to draw a circle.
The length of the radius is determined by the drawing
point chosen on the leg.
The radius can be 3cm, 5cm, 7cm, 9cm or 11 cm.
a. Mark the center point of a circle.
b. Place the GeoLeg center over the point.
c. Use a pencil to hold the center as a pivot point.
d. Place a second pencil in the drawing point.
e. Rotate the pencil to draw the circle.
f. Use the straight edge to draw the radius and record
its measure.

4. Trace a circle using GeoLeg as a pattern. GeoLeg has a radius of 2.2cm.
a. Mark a center point.
b. Use a pencil or toothpick to hold the center as a pivot point.
c. Use a pencil to trace a circle around GeoLeg, pushing the legs
out of the way.

5. Concentric circles are two or more circles
that have the same center.
Draw concentric circles.
a. Mark a center point.
b. Draw circles with different radii around
the center point.

180
6. Art Design to try.
a. Mark a center and draw concentric circles with radii of
3cm and 5cm.
b. Mark points on the 5cm circle at 0, 90, 180 and 90.
c. Connect the opposite points on the circle with          90                        90
diameters.
d. Draw squares by connecting 0 to 90, 90 to 180, 180 to
90 and 90 to 0 in both circles.
e. Develop a pattern of colors.
0
7. Inscribe a hexagon in a circle.                                        180
a. Mark a center and draw a circle.
b. Using the GeoLeg circle as a pattern, mark points at
0, 60, 120, 180, 60, 120.                              120                       60
c. Write the measures outside the circle.
d. Connect points (consecutively) 0 to 60, 60 to 120,
120 to 180, 180 to 60, 60 to 120, 120 to 0.
e. Draw a triangle:                                        60                       120
connect points 0 to 120, 120 to 60, 60 to 0
f. Draw another triangle:
connect points 60 to 180, 180 to 120, 120 to 60.                       0
Sample Lesson

Each student needs 4-6 GeoLegs for building polygons.

888-595-5347

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