Can someone refresh my memory?

Started by
4 comments, last by i1977 21 years, 9 months ago
Hi! I''m beginning 3D programming, and in order to better understand some of the algorithms that I read about, I''d like someone to refresh my memory about sin, cos and tan... My math classes are a little far behind me and I have forgotten what these do exactly. Can someone give me a clear explanation? Thanks!
Frederic FerlandStrategy First, Inc.http://www.strategyfirst.com
Advertisement
Well, remember Triangles?
Sine, Cosine, and Tangent relate to Side lengths of a triangle given two other lengths.
Remember SohCahToa ? It stands for:
Sine = Opposite / Hypotenuse
Cosine = Adjacent / Hypotenuse
Tangent = Opposite / Adjacent

You then take 2 side lengths and solve for the angle measure by means of one of those functions, or one angle and one side and solve for the other.. Depending on the two lengths, you use a function. If you have the hypotenuse and its adjacent side(not the opposite from the angle) then you would use the Cosine function. cos = adjacent / hypotenuse. Plug in the two values you have and the third comes.
When you have to lengths you use inverse sin, cos, tan. This results in the angle measure.

Get it? All you wanted was to understand the relevance to them in 3D programs? I hope this was enough.

"It's easy to make things hard, but it's hard to make things easy."
Thanks! That''s what I wanted to know. Just one more question. When looking at an angle in the triangle, two sides form that angle. How do I know which one to use for the "Adjacent" value in those formulas?
Frederic FerlandStrategy First, Inc.http://www.strategyfirst.com
That only works for right angled triangles doesn''t it? For other types I think the relationship is a/sinA=b/sinB=c/sinC; a being a side, and A being the angle opposit that side. Don''t know how to apply it though...
Best thing to do, rather than trying to Q&A your way to math refreshers is to google the math you are trying to learn:

for instance, in this case: "Trigonometry tutorial" revealed some very good sites that can re-walk you through trig.

here''s one of them:

http://www.sosmath.com/trig/trig.html

-me
Thanks Palidine, I''ll take a look!
Frederic FerlandStrategy First, Inc.http://www.strategyfirst.com

This topic is closed to new replies.

Advertisement