Tricky Trig

programming flash
1

Hi,

Trying to learn trigonometry and still having some difficulty understanding the basic concepts. For example when you say “the sine of A” you are actually referring to the length of a? As in the pic. Also, this is important for me to understand, sine is a way of finding out the length of c if you know the length of the hypotenuse and the angle A? Is this correct? Because every webpage I’ve seen trying to explain these concepts doesn’t really explain WHY the sine function is there, what it’s purpose is. If someone could shed some light as to why these functions are then I could go on learning about it, otherwise I’ll just have to memorize stuff without understanding it:)

Thanks for any help!

2

yeea the sine does find the opposite (uh if i remmeber correctly :))

Not sure what you want me to make clear for you (didn’t you learn trig in math?)

oh yah just remember soh cah toa :slight_smile:

3

Well, it’s funny but I remember NOTHING from math I did in highschool hehe…too many distractions at that age I guess.
So how does the sine function find c from the angle and hypotenuse?

4

sine of A isnt necessarily a, its a value from -1 to 1 which can be used to represent a in terms of c.

a = sine(A) * c

cosine goes to b

b = cosine(A) * c

You can find more explanation in the rotating a vector thread in the best of. let me snag the link for ya

http://www.kirupaforum.com/forums/showthread.php?s=&threadid=12181

5

Sine of A means the sine of angle A…or the vertical position of a certain angle at some degree (or radian) of circular motion of radius 1.
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ok…you didn’t get that.
here:

see if you can understand this.

6

Thank you very much for taking the time to reply:) That post is gold senocular, reading it now. I suspect I’m asking a difficult question here, but how is the sine calculated? sin(26) = .438
How do you arrive at that number?

7

An easy way for me to remember is from a mneumonic from high school.
SOHCAHTOA
Sine = Opposite / Hypotenuse
Cosine = Adjacent / Hypotenuse
Tangent = Opposite / Adjacent

This will give you the measurement of the angle in radians.

8

Nocturn, you cant really calculate Sine, you can only approximate it… there are several sine approximation formulas, im not sure which one Flash uses… for examples, read this page

9

Ok, it’s starting to slowly sink in :slight_smile: I didn’t think that calculating sine was that complicated. Funny that I just did 26/(180/pi) and I got about .453

10

26/(180/pi) is the equivalent to 26 degrees in radians… its not the value of sin(26) :slight_smile: