parametric curves

manps

hi,
I need help on sketching the curve for x=2sect, y= 3tant, -(pi)/2< t <(pi)/2

thanks

Reply 1

Gaz031

manps

hi,
I need help on sketching the curve for x=2sect, y= 3tant, -(pi)/2< t <(pi)/2

thanks

You can either plug in some values for t to find some points and plot the curve or you could use (secx)^2-(tanx)^2=1 to find the cartesian equation which might help you to visualise it more.
The curve is a hyperbola i think.

Reply 2

Syncman

off the top of my head that looks like a hyperbola (ish). But the best way would be to use a graphical calculator. Put it in parametric mode. And stick it in.

Reply 3

trixx

Syncman

Put it in parametric mode. And stick it in.

I didn't know you could do that. If i could only find that darn manual... :tsr:

Reply 4

SsEe

-(pi)/2< t <(pi)/2 means that x=2sect is always positive so it's the x>0 branch of a hyperbola crossing x axis at x=2 (when t=0 you get (2,0) )

Reply 5

Syncman

trixx

I didn't know you could do that. If i could only find that darn manual... :tsr:

I only know hwo to do it on the casio ones.

Reply 6

Feria

I would do it the y=mx+c way because you have a sec and tan:

x=2sect
x²=4sec²t
y=3tant
y²=9tan²t

tan²=sec²t-1

y²=9(sec²-1)
y²=9(x²/4 -1)

and work from there...

I only knwo how to do it on the casio ones... but if you have a graph option on the main menu and go under it, if there is any TYPE button, whatever your calculator parametrics (Parm) will be there if anywhere.