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  • HP Prime Trig Simplify

    From [email protected]@21:1/5 to All on Sun Nov 4 13:58:04 2018
    Is there a way to program the HP Prime to understand things like "[1-COS^2(x)/COS^2(x)]" is equal to "TAN(x)"? The HP Prime seems to struggle when it comes to trig identities.

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  • From Irl@21:1/5 to [email protected] on Mon Nov 5 06:13:06 2018
    On Sunday, November 4, 2018 at 4:58:06 PM UTC-5, [email protected] wrote:
    Is there a way to program the HP Prime to understand things like "[1-COS^2(x)/COS^2(x)]" is equal to "TAN(x)"? The HP Prime seems to struggle when it comes to trig identities.

    Your specific example is problematic. Presumably what you meant was something like
    [1-COS^2(x)]/COS^2(x)
    not
    [1-COS^2(x)/COS^2(x)]
    which, by the way is equal to TAN^2(x), not TAN(x). If instead you meant SQRT([1-COS^2(x)]/COS^2(x))
    then that is either TAN(x) or -TAN(x). I don't have a Prime but if you put in the correct formulas does it work more as you expect?

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  • From [email protected]@21:1/5 to All on Mon Nov 5 06:32:26 2018
    Yes, what that's what I meant. But no, it still just gives back my entry of [COS^2(x)-1]/COS^2(x). Is this a problem with other HP calcs, or is the Prime the only one with a CAS or what? I know the TI nSpire CAS's do fine with trig identities.

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  • From [email protected]@21:1/5 to [email protected] on Mon Nov 5 11:50:42 2018
    On Monday, November 5, 2018 at 8:32:29 AM UTC-6, [email protected] wrote:
    Yes, what that's what I meant. But no, it still just gives back my entry of [COS^2(x)-1]/COS^2(x). Is this a problem with other HP calcs, or is the Prime the only one with a CAS or what? I know the TI nSpire CAS's do fine with trig identities.

    HP 50-g returns TAN^2(x) when TRIGTAN is applied to the formula.

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  • From [email protected]@21:1/5 to [email protected] on Mon Nov 5 17:54:40 2018
    On Monday, November 5, 2018 at 1:50:45 PM UTC-6, [email protected] wrote:
    On Monday, November 5, 2018 at 8:32:29 AM UTC-6, [email protected] wrote:
    Yes, what that's what I meant. But no, it still just gives back my entry of [COS^2(x)-1]/COS^2(x). Is this a problem with other HP calcs, or is the Prime the only one with a CAS or what? I know the TI nSpire CAS's do fine with trig identities.

    HP 50-g returns TAN^2(x) when TRIGTAN is applied to the formula.

    So it does at least have that functionality. That's a good step in the right direction I suppose. Would there be (any) way for me to get the calculator to do something like that automatically? That's obviously the simplest answer. I don't think I should
    have to run the answer through another function. Plus, if I'm doing a rather complex CAS computation with trig, I don't want to have to reverse engineer what the calculator did just so I can simplify using trig identities. Is there a way to rewrite/
    expand how the calculator handles simplifying trig expressions to accomplish this?

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  • From Bruce Horrocks@21:1/5 to [email protected] on Wed Nov 7 18:45:48 2018
    On 05/11/2018 14:32, [email protected] wrote:
    Yes, what that's what I meant. But no, it still just gives back my entry of [COS^2(x)-1]/COS^2(x). Is this a problem with other HP calcs, or is the Prime the only one with a CAS or what? I know the TI nSpire CAS's do fine with trig identities.


    Using the PC emulator, freshly reset, in CAS mode, I get:

    (cos(x)^2-1)/cos(x)^2 => (cos(x)^2-1)/cos(x)^2
    trigtan(ans) => -tan(x)^2

    --
    Bruce Horrocks
    Surrey
    England
    (bruce at scorecrow dot com)

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