09-22-2012 06:04 AM
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.
I get -(-1/80 sin 5x)-(-5/48) sin (3x)- (-5/8) sin x
How do I get the textbook answer?
09-22-2012 07:14 AM
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!
09-25-2012 11:37 AM
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
09-25-2012 09:09 PM
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....