Logo: Triangles
Page 1
Exploring Triangles
As you know from Geometry class, triangles have 3 sides and 3 angles. A square has 4 each.
TRIANGLE RULES
 Equilateral (3 equal sides and angles)
 Isosceles (2 equal sides and angles)
 Scalene (0 equal sides and angles)
 The sum of all 3 angles in a triangle is 180.
Explore in Logo
1. Start with a clear screen. Draw a line and make a turn.
Type: fd 100 rt 120
2. Draw a 2nd line Type:
fd 100
3. The diagrams below show the angles formed when you turned 120°. Figure out missing angles below.
Turtle turned 120° to the right.
Figure out other angles formed.
How to determine Turn Amount
Turn Amount = 180 – Angle desired
120°
Suppose you want a 30° angle
Turn Amount = 180 – 30 = 150
Suppose you want a 45° angle
Turn Amount = 180 – 45 = 135
SPECIAL TRIANGLES
1. Open the editor and start with a blank screen (no code).
2. Create the 2 procedures shown in the diagram below. eqtriangle and isotriangle
EQUILATERAL TRIANGLE (60-60-60 and = SIDES)
to eqtriangle :side
repeat 3[fd :side rt ____]
end
Example to Try
eqtriangle 50
Hint: 180 – angle to form
50
60°
50
60°
60°
50
(points to the right)
ISOCELES RIGHT TRIANGLE (45-45-90)
to isotriangle :side
fd 1 * :side
rt ____
fd (sqrt 2) / 2 * :side
rt ____
fd (sqrt 2) / 2 * :side
rt ____
Example to Try
isotriangle 150
45°
1
.7071
2
2
45°
150
106
90°
90°
45°
end
.7071
2
2
45°
106
3. Save your code as triangles in your Logo folder. Show me your code when done.
EXPLORE IN LOGO
4. Draw equilateral triangles that point in different directions. Hint:
a. Draw equilateral triangle with sides of 75 pointing left.
b. Draw equilateral triangle with sides of 40 pointing down
c. Draw equilateral triangle with sides of 60 pointing up
5. Draw isosceles triangle using 50 as the side.
you do this by turning rt 30, 60, or 90.
hint: rt ____ eqtriangle ____
hint: rt ____ eqtriangle ____
hint: rt ____ eqtriangle ____
hint: isotriangle ____
6. Now, redo but turn turtle some (try rt 90) then draw same isosceles triangle. hint: rt 90 isotriangle ____