My Nspire CX CAS driving me nuts..derivative and degrees.. please help a college student!

[rbuljo]

hi, I`m sure I is my own fault because I`ve never owned a Ti calculator before.. 

im currently getting an engineers degree, and switched calcs from casio to Ti.

but 1st problem.

trying to derivative:

d/dt 1.152 sin(314t) should be : 361.728 Cos(314t). chain rule and the lots..

just see the answer at wolframalpha http://www.wolframalpha.com/share/clip?f=d41d8cd98f00b204e9800998ecf8427erptjjq4fej

but my Ti answers 6.313 Cos (314t) ??

2nd. problem. this has boggered me for a while.

0.77+1.53 x -90degrees  should be: 1.713 -63.28degrees

Ti just states "Syntax" failure when trying to enter the degrees..?

what am I doing wrong? please help..

[Epi Van Winsen]

Look at the settings (home settings documentsettings)

In radians you get the experts results. Your calculator is  in degrees and gives unexpected(?) results.

Best regards

Epi van Winsen

evwi...@gmail.com

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[Sean Bird]

From the HOME screen press 5 for Setting and change the document settings so that it is radians (this is the default anyway). The second answer below shows what you get if you are in degrees. The third answer shows what you get if you say that it is 314 degrees. You can find the degree (or radian, etc) symbol by press the pi button on the bottom left.

Your second question is unclear to me, so I'll let someone else give you some more details for that one.

[rbuljo]

thank you so much Bird and Winsen!

second question is better explained here. :

on my ol casio i get the answer right out like this   "1.713 -63.28degrees".

and it is the right answer, calculating some load currents in transformers. 

[rbuljo]

nobody got any ideas?

[Sean Bird]

The angle symbol is for geometry text, not calculations. e.g. Angle A = 15 degrees

If you want 0.77 + 1.53*(-90degrees), use the degree symbol which you can find in pi (with the 3.2 OS).

However, I don't think that is really what you want since you say your answer should be 1.713-63.28degrees. 

All the TI was told to do was add two things together and it converted the -90 degrees into radians.

It looks like you are trying to do some kind of vector problem where you get a vector solution.

Trying to better understand what you were asking, I looked up transformer load currents and found 

"Full load current can be calculated by the formula given below:

P=SQUARE ROOT OF 3*V*I*POWER FACTOR"

So I'm not sure what you are really trying to do. I'm interested in what the original question actually says (or what your really put into you previous calculator).

On Tue, Sep 11, 2012 at 4:30 PM, rbuljo <bu...@dsolutions.no> wrote: