# P4 Polar Co-ords HELP!!!!Watch

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#1
Could someone explain Polar Co-ords to me? I've read the P4 Heineman Book and I get how the co-ords (r, theta) relate to (x,y) but I don't think I truely understand Polar Co-ordinates, as I don't have a clue what the curves/lines of polar equations look like!!! How would I draw something like r.cos[theta] = 2?! I've looked in all my maths books but none of them really explain Polar Co-ords, only go over how to transfer from a polar eqtn to cartesian nd vice versa! Please help! Thanks!
0
14 years ago
#2
xi + yj = r(cos[theta]i + sin[theta]j)

So r.cos[theta] = x. The line you have is therefore just the line x=2

I know these arent vectors, but its the same idea.
0
#3
Thanks - an interesting idea!

How would I go about drawing something far more complicated however, without having to plot points?
0
14 years ago
#4
(Original post by Hoofbeat)
Thanks - an interesting idea!

How would I go about drawing something far more complicated however, without having to plot points?
with great difficulty

fermat or someone explaiend something before but i didnt really follow; plotting points is by far the easiest way, unless you memorise the standard forms (cardioid, lemniscate etc).

or if you use a graphical calculator
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#5
(Original post by kikzen)
with great difficulty

fermat or someone explaiend something before but i didnt really follow; plotting points is by far the easiest way, unless you memorise the standard forms (cardioid, lemniscate etc).

or if you use a graphical calculator
Where's fermat when you need him?! lol. Thanks anyways
0
14 years ago
#6
(Original post by Hoofbeat)
Where's fermat when you need him?! lol. Thanks anyways
hi again

it was bezza that was saying it
http://www.uk-learning.net/t51038.html
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14 years ago
#7
Think about what values for theta (if any) give r = 0, and what values give a max or min value for r. Also consider how r varies as theta runs from 0 to pi. Think about whether the curve is symetric at all (replace t with -t) and remember that by convention, r>0
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