MDI Parent Form: Child Forms when called again do not appear in Maximized State

I have added follwing in my MDIParent1.cs file

public static Form1 frm1 = new Form1();
        public static Form2 frm2 = new Form2();
        public static Form3 frm3 = new Form3();

private void MDIParent1_Load(object sender, EventArgs e)
        {

            frm1.MdiParent = this;
            frm2.MdiParent = this;
            frm3.MdiParent = this;
            frm1.Show();
        }

Then I set the WindowsState property of all three forms to Maximized.

in Form1.cs

private void button1_Click(object sender, EventArgs e)
       {
                      this.Hide();
           MDIParent1.frm2.Show();
       }

in Form2.cs

private void button1_Click(object sender, EventArgs e)
        {
            this.Hide();
            MDIParent1.frm3.Show();

        }

in Form3.cs

private void button1_Click(object sender, EventArgs e)
        {
            MDIParent1.frm1.Show();
            this.Hide();
        }

I don't problem when I click on buttons of Form1, 2 resp. once.
but wen I press Button of Form3 I get Form1 not in maximized form but in restored form.
I want that form1 to appear in Maximized state.
Wat should I do?
Please Help