Add perimeter calculations in maths folder

src/main/kotlin/math/Perimeter.kt

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+package math
+
+import java.lang.IllegalArgumentException
+import kotlin.math.pow
+
+/**
+ * Calculate the perimeter of a rectangle
+ *
+ * @param length length of rectangle
+ * @param width width of rectangle
+ * @return perimeter of given rectangle
+ */
+fun perimeterOfARectangle(length: Double, width: Double) =  when {
+    length > 0 && width > 0 -> 2 * (length + width)
+    else -> throw IllegalArgumentException("Length and Width must be positive")
+}
+
+/**
+ * Calculate the perimeter of a square
+ *
+ * @param sideLength side length of square
+ * @return perimeter of given square
+ */
+fun perimeterOfASquare(sideLength: Double) =
+    when {
+        sideLength > 0 -> 4 * sideLength
+        else -> throw IllegalArgumentException("Side Length must be positive")
+    }
+
+/**
+ * Calculate the perimeter of a triangle
+ *
+ * @param base base of triangle
+ * @param sideLength1 side length of triangle
+ * @param sideLength2 other side length of triangle
+ * @return perimeter of given triangle
+ */
+fun perimeterOfATriangle(base: Double, sideLength1: Double, sideLength2: Double) =
+    when {
+        base > 0 && sideLength1 > 0 && sideLength2 > 0 -> base + sideLength1 + sideLength2
+        else -> throw IllegalArgumentException("Base and Sides of the triangle must be positive")
+    }
+
+/**
+ * Calculate the perimeter of a circle
+ *
+ * @param radius radius of circle
+ * @return perimeter of given circle
+ */
+fun perimeterOfACircle(radius: Double) =
+    when {
+        radius > 0 -> 2 * Math.PI * radius
+        else -> throw IllegalArgumentException("Radius must be positive")
+    }

src/test/kotlin/math/PerimeterTest.kt

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+package math
+
+import org.junit.Test
+import java.lang.IllegalArgumentException
+
+class PerimeterTest {
+    @Test
+    fun testPerimeterOfARectangle() = assert(perimeterOfARectangle(10.0, 5.0) == 30.0)
+
+    @Test
+    fun testPerimeterOfASquare() = assert(perimeterOfASquare(5.0) == 20.0)
+
+    @Test
+    fun testPerimeterOfACircle() = assert(perimeterOfACircle(1.0) == 2 *Math.PI)
+
+    @Test
+    fun testPerimeterOfATriangle() = assert(perimeterOfATriangle(5.0, 10.0, 10.0) == 25.0)
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testPerimeterWithNegatives() {
+        perimeterOfARectangle(-1.0, 0.0)
+        perimeterOfASquare(-1.0)
+        perimeterOfACircle(-1.0)
+        perimeterOfATriangle(-1.0, 1.0, 1.0)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testPerimeterWithZeros() {
+        perimeterOfARectangle(0.0, 0.0)
+        perimeterOfASquare(0.0)
+        perimeterOfACircle(0.0)
+        perimeterOfATriangle(0.0, 1.0, 1.0)
+    }
+}