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HP Forum Archive 21

 Trig vs hyperbolic handling differences in Prime CASMessage #1 Posted by Michael de Estrada on 8 Nov 2013, 2:35 p.m. I posted this previously, but received no response so I'm trying again . When I enter COS(x)^2+SIN(x)^2 in CAS I get the result 1, which is correct since this result is true regardless of the value of x. However, if I enter COSH(x)^2-SINH(x)^2 in CAS I should also get 1 as a result, however, I simply get COSH(x)^2-SINH(x)^2 as a result instead. If I replace x with a numerical value instead, then I get the proper result of 1. Why ? And yes I am in radians mode and have Exact unchecked when I do this.

 Re: Trig vs hyperbolic handling differences in Prime CASMessage #2 Posted by Mark Hardman on 8 Nov 2013, 5:49 p.m.,in response to message #1 by Michael de Estrada Try using hyp2exp: ```simplify(hyp2exp(cosh(x)^2-sinh(x)^2)) ``` Gives you the answer you are looking for.

 Re: Trig vs hyperbolic handling differences in Prime CASMessage #3 Posted by Michael de Estrada on 8 Nov 2013, 6:06 p.m.,in response to message #2 by Mark Hardman Thank you very much. Giving it some thought, this makes a lot of sense because while trig functions like cosine and sine are primary, hyperbolics like cosh and sinh are derived from the exponential function, which is primary.

 Re: Trig vs hyperbolic handling differences in Prime CASMessage #4 Posted by Mark Hardman on 8 Nov 2013, 6:26 p.m.,in response to message #3 by Michael de Estrada Agreed. There is value in seeing the intermediate result of: ```((exp(x)+1/exp(x))/2)^2-((exp(x)-1/exp(x))/2)^2 ```

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