Hi Steve, You Wrote:
> Edley, John, > > Another easy way and reliable to approximate 15 degrees - > > Use the fact that tan(15) is very close to 1/4 (only 7% error) > > Take a length of string, bring the ends together and pull out the loop > until tight. This gives you the half length of the string. Repeat the > process with the doubled string, to get the quarter length. Mark off where > the quarters are. > > Now place one end of the string at the centre of your intended wedge and > stretch it in the direction required for one side of the wedge. Make a > mark on the surface at the end of the piece of string. Judging by eye what > is the perpendicular to this, now position the string to be at right > angles to your first line and make your second mark at the quarter length. > > Et voila, you have a triangle with the two long sides separated by 15 > degrees (closer to 14 actually, but still a good enough approximation for > a campsite sundial) > > Steve That is a good idea! , so I started looking for easy to remember ratios that were close to the tangent of 15 degrees and discovered that 4/15 is accurate to better than 1/2 percent and might be easy to remember because of the 15 in the denominator. Thanks! Edley.
