added snippet VectorAngle

snippets/vectorAngle.md

@@ -0,0 +1,36 @@
+---
+title: vectorAngle
+tags: math,intermediate
+---
+
+Returns the angle (theta) value between two vectors.
+
+Use `Math.trunc()` to pick the integer value of length. Use `slice()` slice the incoming array into individual vectors. 
+Use `forEach()`, `Math.pow()` and `Math.sqrt()` to iterate over the vectors and calculate the magnitude of each vector and the scalar product.
+Use `Math.acos()` to calculate arccos and get the theta.
+
+
+```js
+const theta = ((...x) =>{ 
+  let half = Math.trunc(x.length / 2);
+  let a = x.slice(0 , half);
+  let b = x.slice(half);  
+
+  let magnitudeOfA = 0;
+  a.forEach((a) => magnitudeOfA += Math.pow(a , 2));
+  magnitudeOfA = Math.sqrt(magnitudeOfA);
+  
+  let magnitudeOfB = 0;
+  b.forEach((b) => magnitudeOfB += Math.pow(b , 2));
+  magnitudeOfB = Math.sqrt(magnitudeOfB);
+  
+  let scalar = 0;
+  a.forEach((a , i) => scalar += a * b[i]);
+  
+  return Math.acos(scalar / (magnitudeOfA*magnitudeOfB));
+});
+```
+
+```js
+theta(3,4,4,3); // 0.283794109208328
+```