How do...

How do you put in code on C++ [(cos^-1) which is found on calculators as shift cos]...

what I am trying to do is solve for theta...

cos (theta) = Fy/Fx

how would i put that in code?

use the acos() function

Do you have an IDE, like Borland CBuilder, MS Visual C++, or anything to that effect? If so, usually you can use the help function to search when you're just looking for a function.

Searching cos would probably yield acos as an alternate result.

I use acos() but, it does not calculate properly

Are you assigning it to an integer variable? Make sure you're using a float.

Quote:

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Originally Posted by MyDestiny

I use acos() but, it does not calculate properly

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Post the code.

what do u mean float?
i didn't assign it to anything

I keep getting...

-1.#IND

as my answer

What are you doing with it?

You either need to use it in an expression or assign it to a variable.

float accepts decimal values. Integers, as you know, cannot - int in C++ is the same as a real-life integer where no decimal values are allowed

All of the trig functions in <cmath> use radians, not degrees. Maybe that will help. (?)

Example

Code:

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#include<stdio.h>
#include<math.h>

int main(){
    double angle = 0.5; /* this is in radians */
    double c = cos( angle );
    double d = acos( c );
    printf( "%f %f %f\n", angle, c, d );
    return 0;
}

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Quote:

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All of the trig functions in <cmath> use radians, not degrees. Maybe that will help. (?)

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Exactly - I suspect this might be where the problem lies. Radians are ugly numbers, almost always involving a decimal point. Degrees are often the opposite - 270deg, 60 deg, 45 deg, etc.

I think MyDestiny might be using integer containers but it's hard to say without seeing the code

I just wanted to let you all know that I figured out the answer... THANKS a bunch for your help! :)