added surface area calc for pyramid

Author: Marko411

src/main/java/com/thealgorithms/maths/Area.java

@@ -1,4 +1,4 @@
-package com.thealgorithms.maths;
+Dpackage com.thealgorithms.maths;
 
 /**
  * Find the area of various geometric shapes
@@ -193,3 +193,24 @@ public static double surfaceAreaCone(final double radius, final double height) {
         return Math.PI * radius * (radius + Math.pow(height * height + radius * radius, 0.5));
     }
 }
+
+
+/**
+ * Calculate the surface area of a pyramid with a square base.
+ *
+ * @param sideLength  side length of the square base
+ * @param slantHeight slant height of the pyramid
+ * @return surface area of the given pyramid
+ */
+public static double surfaceAreaPyramid(final double sideLength, final double slantHeight) {
+    if (sideLength <= 0) {
+        throw new IllegalArgumentException("Must be a positive sideLength");
+    }
+    if (slantHeight <= 0) {
+        throw new IllegalArgumentException("Must be a positive slantHeight");
+    }
+    double baseArea = sideLength * sideLength;
+    double lateralSurfaceArea = 2 * sideLength * slantHeight;
+    return baseArea + lateralSurfaceArea;
+}
+