Help with using real or unsigned data types in VHDL.

[scorpiosidewinder]

I have real data that has to be used in a VHDL program.
For Example: If A, B and C are real data types. How do I use them in a VHDL program to perform arithmetic operations on them.
If A, B and C were integers then... this below program works..
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity circuit1 is
Port ( A : in integer;
B : in integer;
C : in integer;
Y : out integer);
end circuit1;

architecture Behavioral of circuit1 is

begin

y <= (A + B) * (C);

end Behavioral;
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How would i make the same program work if A, B and C were real data types...
I tried using "real" instead of "integer".. but it did not work...
Also could someone please give a program to find the cosine value of an angle?? Pleaseeee....

Thank you... I really appreciate it...