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Pedro Miguel Pimienta Morales
Asked: 2020-05-03 16:13:14 +0800 CST 2020-05-03 16:13:14 +0800 CST

Convert radians to degrees

  • 772

I am performing a calculation to obtain a value in degrees, but I have come across that the result of a JavaScript operation , involving the types of trigonometric operations, returns these values ​​in radians.

Formula

23.45 * sin(360 * ((284 + dn)/365))

So I perform in JavaScript as follows:

var miVariable = 23.45 * Math.sin(360 * ((284 + 196)/365));
console.log(miVariable);

The returned value is 19.15 , of course, rounding the final value.

The problem is that JavaScript gives the result in radians, and I want it in degrees. I searched, and the solution they give is, multiply the result in radians as follows:

miVariable * (180/Math.PI);

...but the returned value is 1097.2141776755263

Similarly, if I multiply the result but only from the calculation of the sine operation , it falls within a possible angle range between -360 and 360 .

var valorSeno = Math.sin(360 * ((284 + 196)/365));
var valorFinal = valorSeno * (180/Math.PI);
console.log(valorFinal);

Similarly, here I still do not multiply by the value 23.45 , since it returns the same value at the end.

The final value I need is 21.51

javascript

4 Answers

  1. Best Answer

    You have to play a little with the conventions to keep all the equivalences.

    You well know that the Math.sin(x) function receives its parameters as radians. The result follows in radians .

    From there, apply the algebra of the school to solve the sine and give a last conversion to obtain the degrees.

    Math.grados = function(radianes) {
  return radianes * 180 / Math.PI;
};

Math.radianes = function(grados) {
  return grados * Math.PI / 180;
};

let antesSeno = Math.radianes(360 * ((284 + 196)/365)),
  miVariable = 23.45 * Math.sin(antesSeno),
  miGrados = Math.grados(miVariable);
console.log(antesSeno);
console.log(miVariable);
console.log(miGrados);

    • 13

  2. You can get the result in degrees, without converting from radians to degrees. Instead, I decided to make a small change to the mathematical formula.

    The original formula is this:

    23.45 * sin(360 * ((284 + dn)/365))

    I just changed the 360to double pi ( 2*Math.PI). Apparently, 180º is the equivalence of pi.

    I have programmed the function so that it adapts to the number of days in the year, that is, if it is a leap year or not.

    var dn = 196
var declinación = (dn,días)=>23.45*Math.sin(2*Math.PI*(284+dn)/días)

function formatear(i,días)
{
  var dec = declinación(i,días)
  var signo = 2*+(dec>=0)-1
  var dec_abs = Math.abs(dec)
  var grados = Math.floor(dec_abs)
  var minutos = Math.floor((dec_abs-grados)*60)
  var segundos = Math.floor(((dec_abs-grados)*60-minutos)*60)
  return i+" "+días+"\t"+grados*signo+"º\t"+minutos+"'\t"+segundos+"''\t"+dec+"\n"
}

console.log(formatear(dn,365))
console.log(formatear(dn,366))

var salida=""
for(var i=1;i<=366;i++)
{
  if(i!=366){salida+=formatear(i,365)}
  salida+=formatear(i,366)
}
console.log(salida)

    • 5

  3. I think the formula to convert this is wrong and it should be like this:

    const dregreesToRadian = deg => deg * Math.PI / 180;
    • 2

  4. I assure you that this formula works:var grados = radianes * (180 / Math.PI);

    • 0