Added areaOfATrapezium function to the math folder of algorithms

src/main/kotlin/math/Area.kt

@@ -1,6 +1,6 @@
 package math
 
-import java.lang.IllegalArgumentException
+import kotlin.IllegalArgumentException
 import kotlin.math.pow
 
 /**
@@ -50,4 +50,22 @@ fun areaOfACircle(radius: Double) =
     when {
         radius > 0 -> Math.PI * radius.pow(2.0)
         else -> throw IllegalArgumentException("Radius must be positive")
-    }
+    }
+
+
+/**
+ * Calculate the area of a trapezium
+ *
+ * @param parallelSide1 one of the parallel side of the trapezium
+ * @param parallelSide2 second parallel side of the trapezium
+ * @param height distance between these two parallel sides of trapezium
+ * @return area of given circle
+ */
+
+fun areaOfATrapezium(parallelSide1: Double, parallelSide2: Double, height: Double) =
+    when {
+        height > 0 && (parallelSide1 > 0 && parallelSide2 > 0) -> ((parallelSide1 + parallelSide2))/2*height
+        else -> throw IllegalArgumentException("Length of both the parallel side and height should be positive")
+    }
+
+

src/test/kotlin/math/AreaTest.kt

@@ -1,7 +1,7 @@
 package math
 
 import org.junit.Test
-import java.lang.IllegalArgumentException
+import kotlin.IllegalArgumentException
 
 class AreaTest {
     @Test
@@ -16,12 +16,16 @@ class AreaTest {
     @Test
     fun testAreaOfATriangle() = assert(areaOfATriangle(5.0, 10.0) == 25.0)
 
+    @Test
+    fun testAreaOfATrapezium() = assert(areaOfATrapezium(6.0, 8.0, 4.0) == 28.0)
+
     @Test(expected = IllegalArgumentException::class)
     fun testAreaWithNegatives() {
         areaOfARectangle(-1.0, 0.0)
         areaOfASquare(-1.0)
         areaOfACircle(-1.0)
         areaOfATriangle(-1.0, 1.0)
+        areaOfATrapezium(-1.0, -1.0, -1.0)
     }
 
     @Test(expected = IllegalArgumentException::class)
@@ -30,5 +34,8 @@ class AreaTest {
         areaOfASquare(0.0)
         areaOfACircle(0.0)
         areaOfATriangle(0.0, 1.0)
+        areaOfATrapezium(0.0, 0.0, 0.0)
     }
+
+
 }