[Term Entry] C# Math-functions: SinCos()

Added documentation for the Math.SinCos() method which returns both
the sine and cosine of a given angle as a tuple. This method is more
efficient than calling Math.Sin() and Math.Cos() separately.

Resolves #7953

Author: ylevental

content/c-sharp/concepts/math-functions/terms/sincos/sincos.md

@@ -0,0 +1,75 @@
+---
+Title: '.SinCos()'
+Description: 'Returns both the sine and cosine of a given angle.'
+Subjects:
+  - 'Code Foundations'
+  - 'Computer Science'
+Tags:
+  - 'Methods'
+  - 'Numbers'
+  - 'Arithmetic'
+  - 'Functions'
+CatalogContent:
+  - 'learn-c-sharp'
+  - 'paths/computer-science'
+---
+
+The **`Math.SinCos()`** class method returns both the sine and cosine of a given angle as a tuple.
+
+## Syntax
+
+```pseudo
+Math.SinCos(angle);
+```
+
+The `Math.SinCos()` method takes only one parameter, `angle`, an angle in radians of type `double`. The method returns a tuple containing both the sine and cosine of the `angle` as `double` values. If the value of `angle` equals `NaN`, `NegativeInfinity`, or `PositiveInfinity`, the method returns `NaN` for both values.
+
+> **Note:** This method is more efficient than calling `Math.Sin()` and `Math.Cos()` separately when both values are needed.
+
+## Example
+
+The following example first converts `45` degrees to radians, then uses the `Math.SinCos()` method to return both the sine and cosine of that angle. Finally, the `Console.WriteLine()` function prints the results to the console:
+
+```cs
+using System;
+
+public class Example {
+  public static void Main(string[] args) {
+    double degrees = 45;
+    double radians = degrees * Math.PI/180;
+
+    var (sine, cosine) = Math.SinCos(radians);
+
+    Console.WriteLine("The sine of " + degrees + " degrees is: " + sine);
+    Console.WriteLine("The cosine of " + degrees + " degrees is: " + cosine);
+  }
+}
+```
+
+The example will result in the following output:
+
+```shell
+The sine of 45 degrees is: 0.7071067811865476
+The cosine of 45 degrees is: 0.7071067811865476
+```
+
+## Codebyte Example
+
+The following example is runnable and returns both the sine and cosine of the `angle` given in degrees:
+
+```codebyte/csharp
+using System;
+
+public class Example {
+
+  public static void Main(string[] args) {
+    // Angle in degrees
+    double angle = 30;
+
+    var (sine, cosine) = Math.SinCos(angle * Math.PI/180);
+
+    Console.WriteLine("The sine of " + angle + " degrees is: " + sine);
+    Console.WriteLine("The cosine of " + angle + " degrees is: " + cosine);
+  }
+}
+```