Well I passed my first semester of Algebra I and understand it fairly well. I got a credit in Geometry, but to tell the truth I didn't understand it and the student helper that graded papers just gave me all Cs. After this I dropped out, so I never even started my second semester of Algebra I or Geometry. Plus this was all almost 8 or 9 years ago.

I'd say my basic Algebra knowledge is still there though. In the sense that I can solve basic algebraic expressions and I remember the order of operations.

Mathematically speaking, geometry is actually much more rewarding than trigonometry (or pretty much any other maths subject learned in high school, I'd say). If you want to learn math properly, I recommend starting there.

Lewzer wrote:

I'm a two time drop out - but far from a dummy (really, its true! - both parts!). The learning style employed by "the education system" does not work well for me. I've been lurking around the site, and from your posts, you seem to be pretty sharp yourself - so perhaps the same is true for you. If that is the case, they don't fall into the trap of trying to force yourself to be taught in the "typical" way.

Strangely enough I got honors on my GED with a score of 666 average and a 780 on my math out of 800 and it's my worst subject. All of my scores were in the 700 area, except for one 680, and then my essay was horrible a 540. I actually failed my essay the first time, because I never really did anything in school. I actually skipped pretty much all my classes and dropped out as a freshman. I only went to math class because the student grader was a senior and she had a thing for me. ;)

Garthor wrote:

You know, thinking back on it, there's very little actual information in Trigonometry. I mean, let's see. Definitions for sin, cos, tan:

sin = o/h
cos = a/h
tan = sin/cos = o/a

A couple common laws:

a/sinA = b/sinB = c/sinC
c2 = a2 + b2 - 2ab*cosC
(that's c squared etc)

See that's what I want to learn it for is mainly cos, sin, arctan, and such. I find them to be used in programming for finding angles which I need to learn. When you say sin = o/h, I have no clue what that means. When I was trying to develop my own pixel projection system I fell short because I had no clue how to find the angle from point A to point B. I know one handles x and one handles y, but that's only because Zaltron was trying to teach me this a couple days ago.

Garthor wrote:

http://upload.wikimedia.org/wikipedia/commons/4/4f/ TrigonometryTriangle.svg

The first three definitions I wrote only hold for right triangles like this one. However, that will generally be the case for anything you do regarding games, so no worries there.

Big letters label the angles, little letters label the sides. The o, h, a I wrote correspond to opposite, hypotenuse, and adjacent, or the sides a, c, b in the picture. The angle of the functions is presumed to be the bottom-left angle. So, rewriting the definitions:

sin(A) = a/c
cos(A) = b/c
tan(A) = sin(A)/cos(A) = a/b

arctan(A) is just 1/tan(A), same with arccos for cos and arcsin for sin.

So, c would be the angle with A being the starting point and B being the destination. I would do get_dist to find a and b and divide those by c for my sin and cos. And that would give me the angle in which something should be able to move?

Garthor wrote:

In the case of a game, a would be M2.y - M1.y, b would be M2.x - M1.y, and c would be sqrt(a*a + b*b). To find the angle from M1 to M2, you would do the arcsin(a/c) or arccos(b/c) or arctan(a/b) but arctan is not a standard, defined function.

There are some complications when the angle gets larger than 90 degrees, but an arctan2 function (Lummox wrote one here) handles that. So, arctan2(M2.x-M1.x, M2.y-M1.y) will tell you the angle between any two atoms M1 and M2.

Well, I understand more than I did. Hopefully I'll be able to implement this knowledge for pixel projectiles and for a bouncing ball effect for some nice arcade type games.

Garthor wrote:

arctan(A) is just 1/tan(A), same with arccos for cos and arcsin for sin.

You mixed up arctan(x) with cot(x) = 1/tan(x) there, as you're probably aware.

arctan is the inverse function of tan:

arctan ( tan(A) ) = A (for 0<=A<90 deg)

This is complicated by the way arctan(x) is often written as tan^(-1)(x), which looks like it should be the same thing as 1/tan(x), but actually isn't.

Oh snap.. This site is sexy. Haha, I appreciate you posting this.

Hmm, If I were you, I would have a firm understanding in algebra before you approach these. Mainly because, all rules derived are because of Algebra.

Besides that, cos, sin, and tan are simply ratios for a right triangle. Because, if you make a triangle right, by putting a parallel line through two rays that make an angle, you can say as you move the line in a perpendicular direction, the size of the triangle expands in proportion to that.

Therefore, functions similar too the concept of cos, sin, tan could be made for any other angle, other than a right - But the clever part in not doing so, is your can separate any non-right triangle into a right one.

After finding out how everything works, every single new rule will be a result of algebra. Hmm, I wonder if this site will tell me what a number divided by zero is?

Id say infinity... Just because when you say 5 divided by 2, you say divide this "5" into 2 parts, then take one part. So, dividing by zero is initially saying to make a number non-discernible as it will not be a part of anything, or anything part of it. Or..something like that, I really shouldnt do Math at night either Lmao >.>