Merge pull request #25 from ieedan/add-triangles-to-math

src/utilities/math/index.ts

@@ -1,5 +1,6 @@
 import * as conversions from './conversions';
 import * as fractions from './fractions';
 import { gcd, gcf } from './gcf';
+import * as triangles from './triangles';
 
-export { gcf, gcd, fractions, conversions };
+export { gcf, gcd, fractions, conversions, triangles };

src/utilities/math/triangles.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, it } from 'vitest';
+import * as math from '.';
+
+describe('right', () => {
+	it('solves for triangle consistently', () => {
+		expect(math.triangles.right.solve({ angle: 30, opposite: 5 })).toStrictEqual({
+			adjacent: 8.660254037844387,
+			angle: 30,
+			hypotenuse: 10.000000000000002,
+			opposite: 5,
+		});
+
+		expect(
+			math.triangles.right.solve({ angle: 30, adjacent: 8.660254037844387 })
+		).toStrictEqual({
+			adjacent: 8.660254037844387,
+			angle: 30,
+			hypotenuse: 10,
+			opposite: 5,
+		});
+
+		expect(math.triangles.right.solve({ angle: 30, hypotenuse: 10 })).toStrictEqual({
+			adjacent: 8.660254037844387,
+			angle: 30,
+			hypotenuse: 10,
+			opposite: 4.999999999999999,
+		});
+	});
+
+	it('throws if 0 angle provided', () => {
+		expect(() => math.triangles.right.solve({ angle: 0, hypotenuse: 10 })).toThrow();
+	});
+
+	it('throws if incorrect arguments were provided due to ignored type error', () => {
+		// @ts-ignore
+		expect(() => math.triangles.right.solve({ angle: 10 })).toThrow();
+	});
+});

src/utilities/math/triangles.ts

@@ -0,0 +1,104 @@
+import { dtr } from './conversions';
+
+export type RightTriangle = {
+	/** Angle in degrees */
+	angle: number;
+	/** opposite length */
+	opposite: number;
+	/** adjacent length */
+	adjacent: number;
+	/** hypotenuse length */
+	hypotenuse: number;
+};
+
+export type SolveOptions =
+	| {
+			angle: number;
+			opposite: number;
+			adjacent?: never;
+			hypotenuse?: never;
+	  }
+	| {
+			angle: number;
+			opposite?: never;
+			adjacent: number;
+			hypotenuse?: never;
+	  }
+	| {
+			angle: number;
+			opposite?: never;
+			adjacent?: never;
+			hypotenuse: number;
+	  };
+
+/** Solves the right triangle based on the angle given and any one of the sides
+ *
+ * @param param0
+ * @returns
+ */
+const solveRight = ({ angle, opposite, adjacent, hypotenuse }: SolveOptions): RightTriangle => {
+	if (angle <= 0) throw new Error(`Invalid value (${angle}) for 'angle'`);
+
+	if (typeof hypotenuse === 'number') {
+		opposite = solveForOpposite({ angle, hypotenuse });
+		adjacent = solveForAdjacent({ angle, hypotenuse });
+	} else if (typeof opposite === 'number') {
+		adjacent = solveForAdjacent({ angle, opposite });
+		hypotenuse = solveForHypotenuse({ angle, opposite });
+	} else if (typeof adjacent === 'number') {
+		opposite = solveForOpposite({ angle, adjacent });
+		hypotenuse = solveForHypotenuse({ angle, adjacent });
+	} else {
+		throw new Error(
+			'Incorrect arguments provided! expected opposite, adjacent, or hypotenuse to be a number'
+		);
+	}
+
+	return {
+		angle,
+		opposite,
+		adjacent,
+		hypotenuse,
+	};
+};
+
+type OppositeSolveOptions =
+	| { angle: number; adjacent: number; hypotenuse?: never }
+	| { angle: number; adjacent?: never; hypotenuse: number };
+
+const solveForOpposite = ({ angle, adjacent, hypotenuse }: OppositeSolveOptions): number => {
+	if (typeof hypotenuse === 'number') {
+		return Math.sin(dtr(angle)) * hypotenuse;
+	}
+
+	return Math.tan(dtr(angle)) * adjacent;
+};
+
+type AdjacentSolveOptions =
+	| { angle: number; opposite: number; hypotenuse?: never }
+	| { angle: number; opposite?: never; hypotenuse: number };
+
+const solveForAdjacent = ({ angle, opposite, hypotenuse }: AdjacentSolveOptions): number => {
+	if (typeof opposite === 'number') {
+		return opposite / Math.tan(dtr(angle));
+	}
+
+	return hypotenuse * Math.cos(dtr(angle));
+};
+
+type HypotenuseSolveOptions =
+	| { angle: number; opposite: number; adjacent?: never }
+	| { angle: number; opposite?: never; adjacent: number };
+
+const solveForHypotenuse = ({ angle, opposite, adjacent }: HypotenuseSolveOptions): number => {
+	if (typeof opposite === 'number') {
+		return opposite / Math.sin(dtr(angle));
+	}
+
+	return adjacent / Math.cos(dtr(angle));
+};
+
+/** Functions for working with right triangles */
+const right = { solve: solveRight };
+
+export { right };