Feature/surface area pyramid

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

@@ -192,4 +192,36 @@ public static double surfaceAreaCone(final double radius, final double height) {
         }
         return Math.PI * radius * (radius + Math.pow(height * height + radius * radius, 0.5));
     }
+
+        /**
+     * Calculates the total surface area of a pyramid with a square base.
+     * Includes both the base area and the slanted triangular sides.
+     *
+     * @param side  the length of one side of the square base
+     * @param slant the slant height of the pyramid
+     * @return the total surface area of the pyramid in square units
+     * @throws IllegalArgumentException if any dimension is zero or negative
+     */
+    public static double surfaceAreaPyramid(final double side, final double slant) {
+        // Validation: both side and slant height must be positive
+        if (side <= 0) {
+            throw new IllegalArgumentException("Side length must be greater than zero");
+        }
+        if (slant <= 0) {
+            throw new IllegalArgumentException("Slant height must be greater than zero");
+        }
+
+        // Base area (square) = side^2
+        double base = side * side;
+
+        // Each triangular face has area = (side * slant) / 2
+        // A square pyramid has 4 faces → multiply by 4 / 2 = 2
+        double lateral = 2 * side * slant;
+
+        // Total surface area = base + lateral area
+        double totalArea = base + lateral;
+
+        // Return the final computed surface area
+        return totalArea;
+    }
 }