Wednesday, December 10, 2008

Similar Triangles

A little geometry rule we use everyday with our computers and may not realize it is the property of similar triangles. A common definition taken from this site is, "Triangles are similar if their corresponding (matching) angles are equal and the ratio of their corresponding sides are in proportion." Every time we scale an image or window we can thank this rule for making it work.

For my engineering work I often make use of similar triangles and simple trigonometry (remember sines, cosines and tangents anyone?) to calculate distances and positions. As long as you stick with right triangles (one of the three angles must be 90 degrees), know the length of one or more sides and know one or more angles, you can determine the remaining lengths and angles. Maybe I'll post something more on this in the future.

I tried to doctor up a poor photo of several of my triangles. The 30/60/90 triangles are ll similar, but alas poor 45/45/90 is not. Not many people use drafting triangles anymore but were once an indispensable tool for draftsmen, architects, graphic designers and illustrators until computers took their place.

Here is another link providing fun and probably forgotten definitions of triangles. Acute and obtuse - who can deny those aren't fun words to say?

By the way I am here in Mexico for work and this Friday is Saint Juan Diego's feast day, a national holiday. Adios!

P.S. The digital photo was altered and scribbled on using GIMP and a Wacom tablet.

No comments: