questions thread

[Mao]

anywayz... anyone knows:
how to get solid of revolutions with TI-89 without doing it manually with the antidifferential equation???(seeking an express way lol)

there is none [that I know of]

Soz for hijacking this thread but how do you highlight something?

hold the 'shift' key (the up-arrow key, next to '2nd' and 'ALPHA') and use the navigational left and right to highlight. You can then use 'cut'/'copy'/'paste' on the selected text, these are located at diamond + '2nd'/shift/'esc'.

[TrueTears]

anywayz... anyone knows:
how to get solid of revolutions with TI-89 without doing it manually with the antidifferential equation???(seeking an express way lol)

there is none [that I know of]

Soz for hijacking this thread but how do you highlight something?

hold the 'shift' key (the up-arrow key, next to '2nd' and 'ALPHA') and use the navigational left and right to highlight. You can then use 'cut'/'copy'/'paste' on the selected text, these are located at diamond + '2nd'/shift/'esc'.

Oh yeah it works, thanks mao!

[monokekie]

here's a real noob one, but does trouble me a lot.

how do you convert ,for eg, 13/2 -----> 6   1/2 by pressing buttons on the calc? ( 89 and 84)
because silly mistakes always occur when i transfer it manually

[lacoste]

here's a real noob one, but does trouble me a lot.

how do you convert ,for eg, 13/2 -----> 6   1/2 by pressing buttons on the calc? ( 89 and 84)
because silly mistakes always occur when i transfer it manually

GREEN DIAMOND ENTER !!

[monokekie]

lol. tkx

and here's another question:

[monokekie]

and this....



i am up to a = positive or negative 5, but am having trouble using the info "direction of motion is greater than pie over two from the positive x axis " to eliminate one, answer says c.

any aidea? tkx

[JuzzLee]

lol. tkx

and here's another question:

(Image removed from quote.)

 ( draw a circular graph then you can see why )

=



now sub into the equation and then rearrange them, take the common factor out

[TrueTears]

lol. tkx

and here's another question:

(Image removed from quote.)

 ( draw a circular graph then you can see why )

=



now sub into the equation and then rearrange them, take the common factor out

Another way to get z2 is to do

so

thus

[ryley]

To work out if it is a is positive or negative 5, try both when you substitute t=pi/4 for the position vector and see which value of 5 does not cause the resultant vector to be in the first quadrant (ie; angle > pi/2)

EDIT: Sorry about that, see TrueTears post below for correct explanation (although in my defense, it was a typo   )

[TrueTears]

To work out if it is a is positive or negative 5, try both when you substitute t=pi/4 for the position vector and see which value of 5 does not cause the resultant vector to be in the first quadrant (ie; angle > pi/2)

The question asks for the direction not the position vector that makes the angle.
Sub a = 5 or -5 into the velocity vector and see which makes an angle with the positive x axis thats larger than pi/2