Trig functions - HP 50g (885 Views)
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Occasional Visitor
FakeIDD
Posts: 1
Registered: ‎09-22-2012
Message 1 of 8 (885 Views)

Trig functions - HP 50g

Hello,

 

I just got HP 50g and I'm learning how to use it. Bit more complicated than the casio I had. I'm trying to integrate cos^5 (x) and the text book answer is 1/5 sin^5 x - 2/3 sin^3 x + sin x. When I work the problem out on paper I get the same answer. However when I use the calculator I get a different answer.

 

RISCH (cos(x)^5,x)

 

I get -(-1/80 sin 5x)-(-5/48) sin (3x)- (-5/8) sin x

 

How do I get the textbook answer?

 

Thank You

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Occasional Advisor
Eertwegh
Posts: 6
Registered: ‎06-28-2012
Message 2 of 8 (870 Views)

Re: Trig functions - HP 50g

Hi FakeIDD!

 

Nice you've chosen the HP50G. But indeed it is a complicated machine!

 

The HP has a lot of commands to convert sin, cos and tan. You can find them in menu TRIG (right-shift 8).

For example, your result on the integration can be converted to the textbook answer with the sequence of commands:

TEXPAND (second page of TRIG, gets rid of 5x etc), TRIGSIN (third page, converts all to sin) and FDISTRIB (in menu CONVERT submenu REWRITE, distributes division over addition).

 

I recomment some playing with all these commands, it's really fun!

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Honored Contributor
Miguel Angel Caporalini
Posts: 2,392
Registered: ‎02-09-2009
Message 3 of 8 (857 Views)

Re: Trig functions - HP 50g

Hi, FakelDD:

 

Welcome to site!.

 

You can see examples, in ... http://h20331.www2.hp.com/Hpsub/downloads/50gSymbolic_integration_of_trig_functions.pdf

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Honored Contributor
pin224466
Posts: 426
Registered: ‎03-01-2012
Message 4 of 8 (851 Views)

Re: Trig functions - HP 50g

[ Edited ]

 

 

integral.jpg

 

 

 

 

 

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Honored Contributor
pin224466
Posts: 426
Registered: ‎03-01-2012
Message 5 of 8 (842 Views)

Re: Trig functions - HP 50g

[ Edited ]

important not to overlook the TRIGSIN operation in Eertwegh's solution.

 

 

 

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Occasional Advisor
Eertwegh
Posts: 6
Registered: ‎06-28-2012
Message 6 of 8 (745 Views)

Re: Trig functions - HP 50g

Anyone interested in trigonometric conversions and the commands the HP50G provides for such manipulations, read this excellent post on HPcalc: http://www.hpcalc.org/hp49/docs/misc/trigmara.zip

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Valued Contributor
Axel59000
Posts: 119
Registered: ‎04-06-2012
Message 7 of 8 (732 Views)

Re: Trig functions - HP 50g

 

Hi Eetwegh !

 

Lot of interesting things in this file ! Thanks for this link ...

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Honored Contributor
pin224466
Posts: 426
Registered: ‎03-01-2012
Message 8 of 8 (715 Views)

Re: Trig functions - HP 50g

yes, very interesting... thanks...

 

from page 1-2 of the document...

 

"So take this expression in the EQW, select the denominator and then press TRIG, so that the

command acts only upon the denominator."

 

Didn't know that the 50G EQW could be used to make a calculator function act on only a part of the equation... wonder if this works for all equation manipulation functions or only a limited selection....

 

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