Added surface area calculation for pyramid (#6853)

Co-authored-by: JonathanButterworth <JonathanButterworth>

Author: JonathanButterworth

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

@@ -48,6 +48,25 @@ public static double surfaceAreaSphere(final double radius) {
         return 4 * Math.PI * radius * radius;
     }
 
+    /**
+     * 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;
+    }
+
     /**
      * Calculate the area of a rectangle.
      *