Added surface area calculation for pyramid

Author: Aymen Al-Tahmschi

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

@@ -192,4 +192,21 @@ 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;
+}
 }