Problem 1
Draw a straight line and plot X anywhere on it.
Use your compass to trace out a circle with radius 1.5 cm. The circle intersects the line at two points. Let's make Y one of those points.
Also from point X, draw a circle of radius 2.5
This second circle will intersect another circle of radius 3.5 and this third circle is centered at point Z.
Check out the diagram below to see what I mean.
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Problem 2
Draw a straight line and plot L anywhere on it.
Adjust your compass to 4 cm in width. Draw a circle around point L.
This circle crosses the line at two spots. Focus on one of those spots and call it M.
Draw another circle centered at point M. Keep the radius at 4 cm.
The two circles intersect at two points. Focus on one of the points and call it N.
The last step is to connect L, M and N to form the equilateral triangle.
See the image below.
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Problem 3
I'm not sure how to do this using a compass and straightedge. I used GeoGebra to make the figure below instead. It's a free graphing and geometry program which is very useful. I used the same app to make the drawings for problem 1 and problem 2 earlier.
