Implement the following two functions: // Returns true if all the sides of the triangle // are same. bool isValid(double side1, double side2, double side3) // Returns the perimeter of an equilateral...

Implement the following two functions:

// Returns true if all the sides of the triangle // are same.

bool isValid(double side1, double side2, double side3)

// Returns the perimeter of an equilateral triangle.
double perimeter(double side1)

The formula for computing the perimeter is perimeter = 3 * side. Write a test program that reads three sides for a triangle and computes the perimeter if the input is valid. Otherwise, display that the input is invalid.