implemantation $15\mathrm{.}1($The Triangle class$)$

Design a class named Triangle that extends GeometricObject. The class contains the following:

Three double data fields named side$1,$ side$2,$ and side$3$ to denote three sides of the triangle.

Constructors:

A no$-$arg constructor that creates a default triangle with each side $1\mathrm{.}0.$

A constructor that creates a rectangle with the specified side$1,$ side$2,$ and side$3.$

The constant accessor and mutator functions for all three data fields.

A constant function named getArea$()$ that returns the area of this triangle.

A constant function named getPerimeter$()$ that returns the perimeter of this triangle.

A constant function named printTriangle$()$ that returns a string that displays the area, perimeter color, and true$/$false to indicate whether filled or not.