In doing renovations to my back yard, I needed to figure out some angles. The back yard is hilly, and the contractor needed to know the angle of the slope. He had measured three lengths of a triangle, and asked me to determine the interior angles.
The lengths were 102", 102", and 90". I fired up AutoCAD, and quickly worked out the angles. How would you approach the problem? The difficulty is knowing where the three lines intersect.
I relied on a technique learned in my days of hand drafting. The solution back then was as follows:
1. Draw one of the three lines. The ends of the line locate the first and second corners of the triangle.
2. Set the compass to the second distance, and draw an arc.
3. Change the compass to the third distance, and draw another arc.
The intersection of the two arcs is the third corner of the triangle. The same technqiue works in CAD, except that we would use circles instead of arcs. With the triangle drawn, the three angles can be measured.
Writing up this tip made me think about how it is easier to draw arcs in hand drafting, and harder to draw arcs with CAD. The opposite is true for circles: harder in hand drafting, easier in CAD. Makes me wonder why.