algorithm: find length of an arc and area of the sector formed by an arc of a circle (#1119)

* Add an algorithm to find length and area of an arc of a circle

* Updated to follow Javascript Standard Style

* Update CircularArc.js

* Update CircularArc.js

* Add tests

* Followed Javascript standard style

Maths/CircularArc.js

@@ -0,0 +1,31 @@
+import { degreeToRadian } from './DegreeToRadian.js'
+
+/**
+   * @function circularArcLength
+   * @description calculate the length of a circular arc
+   * @param {Integer} radius
+   * @param {Integer} degrees
+   * @returns {Integer} radius * angle_in_radians
+   * @see https://en.wikipedia.org/wiki/Circular_arc
+   * @example circularArcLength(3, 45) = 2.356194490192345
+   */
+function circularArcLength (radius, degrees) {
+  return radius * degreeToRadian(degrees)
+}
+/**
+   * @function circularArcArea
+   * @description calculate the area of the sector formed by an arc
+   * @param {Integer} radius
+   * @param {Integer} degrees
+   * @returns {Integer} 0.5 * r * r * angle_in_radians
+   * @see https://en.wikipedia.org/wiki/Circular_arc
+   * @example circularArcArea(3,45) = 3.5342917352885173
+   */
+function circularArcArea (radius, degrees) {
+  return Math.pow(radius, 2) * degreeToRadian(degrees) / 2
+}
+
+export {
+  circularArcLength,
+  circularArcArea
+}

Maths/test/CircularArc.test.js

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+import { circularArcLength, circularArcArea } from '../CircularArc'
+
+describe('circularArcLength', () => {
+  it('with natural number', () => {
+    const arcLengthOfOneThirty = circularArcLength(1, 30)
+    const arcLengthOfThreeSixty = circularArcLength(3, 60)
+    expect(arcLengthOfOneThirty).toBe(0.5235987755982988)
+    expect(arcLengthOfThreeSixty).toBe(3.141592653589793)
+  })
+})
+
+describe('circularArcArea', () => {
+  it('with natural number', () => {
+    const arcAreaOfOneThirty = circularArcArea(1, 30)
+    const arcAreaOfThreeSixty = circularArcArea(3, 60)
+    expect(arcAreaOfOneThirty).toBe(0.2617993877991494)
+    expect(arcAreaOfThreeSixty).toBe(4.71238898038469)
+  })
+})