How to Circumscribe an Equilateral Triangle
Triangles are closed two-dimensional figures that have three sides and three angles. They vary in type depending on the proportion of the sides. When none of the sides is the same, you have a scalene triangle. If two sides are equal in length, the triangle is isosceles. When all three sides are the same, the triangle is equilateral. Circumscribing a triangle means creating a circle around a triangle that intersects with each of the triangle's corners. To find the center of the circumscribed circle, you must first find the center of the triangle.
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Instructions
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1
Measure one side of the triangle and find the midpoint.
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2
Line up the center of the protractor with the center of the side.
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3
Mark the 90-degree point over the center point of the triangle side.
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4
Draw a line connecting the center point of the triangle's side and the 90-degree point. This line is perpendicular bisector of the side of the triangle.
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5
Repeat Steps 1 through 4 for one other side.
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6
Extend the lines until they cross. If the triangle is obtuse, you will have to extend the lines outside the triangle.
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7
Place the point of the compass on the point where the bisectors cross.
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8
Pivot the pencil while holding the point steady in the center of the triangle. Draw a circle all the way around the triangle, touching each of the triangle's vertices.
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Tips & Warnings
For an acute triangle, the center point of the circumscribing circle will be inside the triangle. For a right triangle, the center point will be on the side opposite the 90-degree angle. In obtuse triangles, the center point will be outside the triangle opposite the obtuse angle.
Use caution when pressing the sharp point of a compass into the paper. Don't press the point so hard that you damage your work surface.
References
- Photo Credit Comstock/Comstock/Getty Images
