(a) \cosh^2 ( -9 ) - \sinh^2 ( -9 ) =

(b)\cosh^2 ( -2 ) - \sinh^2 ( -2 ) =

(c)\cosh^2 ( 1 ) - \sinh^2 ( 1 ) =

(d)\sinh^2 ( 9 ) - \cosh^2 ( 9 ) =

Note:\sinh^2 (x) is defined as ( \sinh (x) ) ^2 and
\cosh^2 (x) is defined as ( \cosh (x) ) ^2

(b)

(c)

(d)

Note:

You can earn partial credit on this problem.