The cone is a solid, while the semicircle is only two dimensional. Are you talking about surface area of cone? Perimeter of base for the cone?
I searched Google under the key words "circle area perimeter" to get this:
http://www.google.com/search?client=safari&rls=en&q=circle+area+perimeter&ie=UTF-8&oe=UTF-8
In the future and for the remainder of your questions, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
formula for peimeter of cone and semicircle
formula for area of cone and semicircle
2 answers
the school swimming pool is 55 yards long and 23 yards wide what is the perimeter