Added surface area calculation for pyramid

Author: dpatino44

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

@@ -1,4 +1,22 @@
 package com.thealgorithms.maths;
+/**
+* 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;
+}
 
 /**
  * Find the area of various geometric shapes