Sin(); and cos() returing strange results

[valkan]

Hey folks. I am trying to find bearing between two points. For that I need to use sin, and cos. However I can not make any good results from these. For example I try something like this:

 float X,Y; 
 void setup() {
 Serial.begin (9600);
 X=cos(38.627);
 Y=sin(4.381);
 Serial.print("X:= ");
 Serial.println(X);
 Serial.print("Y:= ");
 Serial.println(Y);
}

What I am getting from it is X=0.60, and Y=-0.95. The actual calculation of cos(38.627) is 0,781225, and sin(4.381)=0,17364. What am I doing wrong?

[LarryD]

Radians vs degrees.

[jremington]

@valkan

What am I doing wrong?

Forgetting to convert from radians to degrees. Multiply the result by (180.0/PI).

[valkan]

Thanks!

[vaj4088]

Don't multiply the result. Multiply the argument.

[jremington]

Indeed, for some reason I was thinking of the inverse functions. For trig function arguments in degrees, convert to radians by multiplying as follows

 X=cos(38.627*PI/180.0);
 Y=sin(4.381*PI/180.0);