If you haven't come here from my page with a programming challenge, it would be best to go there NOW. You will get a chance to return here, when the appropriate time comes.

The "trick to seeing the answer to "how do we get "the number" comes in two parts.

Start with "What would the number be if AB were 1cm?"

Remember that we know, from sine tables, that in the following, if AC is 1cm, then BC is 0.38cm

But! When we wanted to draw a 40 degree angle, we didn't even have a triangle, let alone a right angle! To do sines (directly) we need a right angle.

Look at...

I hope you said "Ah!"? (If not, study the diagram again.)

We aren't going to try to draw CAB and BAD, but do you see how each of them is a right angle triangle, with a 30 degree angle? As such, if AC and AD are each 1cm long, then CB and BD are each 0.38cm long, and thus we know that the chord (CD) of a 60 degree angle, at a radius of 1cm, is 0.68cm.

That's the hard part done. Go back and re-read it until you really understand it. Properly!

That's all well and good, if AC is 1cm. What if it isn't? Easy! The number we want (the length of AD) is directly proportional to the length of AC. (If AC is 5.28 cm, then AD is 5.28 times what it was when AC was 1cm.)

Here's a link to the main page of this discussion... but if you came here from there, just close this page... the page you came from should be "underneath" this page.

Search across all my sites with the Google search button at the top of the page the link will take you to.
Or...

Search just this site without using forms,
Or... again to search just this site, use...

The search engine merely looks for the words you type, so....
  *!  Spell them properly   !*
  Don't bother with "How do I get rich?" That will merely return pages with "how", "do", "I", "get" and "rich".

I have other sites. My Google custom search button will include things from them....
   One of my SheepdogGuides pages.
   My site at Arunet.

Ad from page's editor: Yes.. I do enjoy compiling these things for you... I hope they are helpful. However.. this doesn't pay my bills!!! If you find this stuff useful, (and you run an MS-DOS or Windows PC) please visit my freeware and shareware page, download something, and circulate it for me? Links on your page to this page would also be appreciated!

This page's editor, Tom Boyd, will be pleased if you get in touch by email.

Page tested for compliance with INDUSTRY (not MS-only) standards, using the free, publicly accessible validator at validator.w3.org. Mostly passes. There were two "unknown attributes" in Google+ button code. Sigh.