how to show multiform calculator with fix size in c# winform

Question

i am trying to make a windows 7 look like calculator i have done the making of basic calculator functions and now i am trying to include scientific and trigonometry functions in calculator and i am trying to do it by making multiple form now here comes the problem
what i am trying to do is when i click on scientific button the form1(main form) change its size and show form2 with no border an attach it self with form1 basic functions and if i click on trigonometry button the form2 (scientific) go and form3(trigonometry) attach it self just like it happen when you change the view of win 7 calculator it expand and show other buttons and when click on standard view it show only basic buttons

how i can do that????


you can see that i attach scientific button to form1 but i want them into form2 and show them only when they needed