This program solves a problem that occurs from time to time. Sizing a circle to fit an existing irregularly shaped object, in this case, a triangle. Trying to scale and position a circle about an object in most drawing programs is difficult at best.
As a side benefit of establishing a circle that circumscribes the triangle, a center point is established that represents the center point of all three vertices of the triangle. This can be useful in many situations as well.
This program computes the diameter of a circle that when properly positioned intersects all three vertices of a triangle (circumscribed).
Begin by creating the triangle ABC. Carefully measure each side. It may be helpful to temporarily label the triangle like the illustration below.
Run the program and enter the length of each side as requested. Record the circle diameter, x position, and y position when they are displayed.
SPECIAL NOTES FOR ADOBE ILLUSTRATOR:
STEP 1: Select the circle tool and while holding down the option key, click on vertex C of the triangle. Enter the diameter value for both the horizontal and vertical dimensions.
STEP 2: With the circle selected, click on the measure tool to select it. Next click on vertex C to start the measurement and then vertex B to finish it. Click OK to dismiss the measurements dialog. This action places the distance and angle measured into Illustrator's move dialog when an object is selected.
Now, holding down the option key, click the arrow tool to bring up the move dialog. Enter the x move value in the "Distance" item of the dialog and click OK. If you used the measure tool as previously describe the angle would already be set.
STEP 3: Holding down the option key click the arrow tool to bring up the move dialog again. Enter the y move value in the "Distance" item.
Some arithmetic is required for the proper angle, which is always 90 degrees greater than the angle of the x move. So add 90 to whatever the previous angle was. If the x angle was 120, then the y angle is 210. If the x angle was -24.59, then the y angle is 65.41.
Remember when working with angles that 360 degrees and 0 degrees are the same. Anytime during your computations resulting angles greater than 360 should have 360 subtracted from them since we don't normally consider the number of revolutions in graphic arts.
