If \[f(x)=\frac{{{2}^{x}}+{{2}^{-x}}}{2}\], then \[f(x+y).f(x-y)\] is equal to

If \[f(x)=\frac{{{2}^{x}}+{{2}^{-x}}}{2}\], then \[f(x+y).f(x-y)\] is

1.	If \[f(x)=\frac{{{2}^{x}}+{{2}^{-x}}}{2}\], then \[f(x+y).f(x-y)\] is equal to
A.	\[\frac{1}{2}[f(x+y)+f(x-y)]\]
B.	\[\frac{1}{2}[f(2x)+f(2y)]\]
C.	\[\frac{1}{2}[f(x+y).f(x-y)]\]
D.	None of these
Answer» C. \[\frac{1}{2}[f(x+y).f(x-y)]\]

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If \[f(x)=\frac{{{2}^{x}}+{{2}^{-x}}}{2}\], then \[f(x+y).f(x-y)\] is equal to

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