Define a java class called RightAngleTriangle.

write another test class called TestRightAngleTriangle and invoke methods of the RightAngleTriangle class 

Instance variables:

1.  Base

2.  Height

Instance methods and Constructors:

1.  Define two constrcutors

2.  Getter and setter methods for each instance variable

3.  ComputeArea method

4.  Compute perimeter method

5.  Define toString()

6.  Define equals ()

After this perform testing in tester class

RightAngleTriangle

public class RightAngleTriangle
{
	private double base;
	private double height;
	
	public RightAngleTriangle() 
	{
		this.base = 0.0;
		this.height = 0.0;
	}
	
	public RightAngleTriangle(double base, double height) 
	{
		this.base = base;
		this.height = height;
	}

	public double getBase() 
	{
		return base;
	}
	public double getHeight() 
	{
		return height;
	}

	public void setBase(double base) 
	{
		this.base = base;
	}
	public void setHeight(double height) 
	{
		this.height = height;
	}
	
	public double computeArea()
	{
		return 0.5 * base * height;
	}
	
	public double computePerimeter()
	{
		return base + height + Math.sqrt((base*base) + (height*height));
	}

	@Override
	public String toString() 
	{
		return String.format("Base: %.1f\nHeight: %.1f", base, height);
	}

	public boolean equals(RightAngleTriangle obj) 
	{
		return base == obj.getBase() && height == obj.getHeight();
	}	
}

TestRightAngleTriangle

public class TestRightAngleTriangle 
{
	public static void main(String[] args) 
	{
		RightAngleTriangle t1 = new RightAngleTriangle(3, 4);
		RightAngleTriangle t2 = new RightAngleTriangle();

		System.out.println("Triangle #1");
		System.out.println("Base: " + String.format("%.1f", t1.getBase()));
		System.out.println("Height: " + String.format("%.1f", t1.getHeight()));
		
		t2.setBase(4);
		t2.setHeight(5);
		
		System.out.println("Area: " + String.format("%.1f", t1.computeArea()));
		System.out.println("Perimeter: " + String.format("%.1f", t1.computePerimeter()));
		
		System.out.println("\nTriangle #2");
		System.out.println(t2.toString());
		
		System.out.println("\nWhether both triangles are equal: " + t1.equals(t2));
	}
}

Step-by-step explanation

SOURCE CODE

RightAngleTriangle

//Class RightTriangle
public class RightAngleTriangle
{
	//Instance variables
	private double base;
	private double height;
	
	//No-arg Constructor
	public RightAngleTriangle() 
	{
		this.base = 0.0;
		this.height = 0.0;
	}
	
	//Parameterized Constructor
	public RightAngleTriangle(double base, double height) 
	{
		this.base = base;
		this.height = height;
	}

	//Getter methods
	public double getBase() 
	{
		return base;
	}
	public double getHeight() 
	{
		return height;
	}

	//Setter methods
	public void setBase(double base) 
	{
		this.base = base;
	}
	public void setHeight(double height) 
	{
		this.height = height;
	}
	
	//Method to calculate area of RightAngleTriangle
	public double computeArea()
	{
		return 0.5 * base * height;
	}
	
	//Method to calculate area of RightAngleTriangle
	public double computePerimeter()
	{
		return base + height + Math.sqrt((base*base) + (height*height));
	}

	//Method to return String representation of RightAngleTriangle
	@Override
	public String toString() 
	{
		return String.format("Base: %.1f\nHeight: %.1f", base, height);
	}

	//Method to check whether two RightAngleTriangle objects are equal or not
	public boolean equals(RightAngleTriangle obj) 
	{
		return base == obj.getBase() && height == obj.getHeight();
	}	
}

TestRightAngleTriangle

//Class TestRightAngleTriangle
public class TestRightAngleTriangle 
{
	//main method
	public static void main(String[] args) 
	{
		//Creating two RightAngleTriangle objects 
		RightAngleTriangle t1 = new RightAngleTriangle(3, 4);
		RightAngleTriangle t2 = new RightAngleTriangle();

		System.out.println("Triangle #1");
		//Calling getter methods of t1 object
		System.out.println("Base: " + String.format("%.1f", t1.getBase()));
		System.out.println("Height: " + String.format("%.1f", t1.getHeight()));
		
		//Calling setter methods to set base & height of t2 object
		t2.setBase(4);
		t2.setHeight(5);
		
		//Calling computerArea() & computerPerimeter() methods of t1 object
		System.out.println("Area: " + String.format("%.1f", t1.computeArea()));
		System.out.println("Perimeter: " + String.format("%.1f", t1.computePerimeter()));
		
		System.out.println("\nTriangle #2");
		//Calling toString() method of t2 object
		System.out.println(t2.toString());
		
		//Calling equals() method
		System.out.println("\nWhether both triangles are equal: " + t1.equals(t2));
	}
}

Please see the attached file for the complete solution