Question

Pre cal help


Change the equation to polar coordinate. y^2=9x

Answer 1

@amistre64

Answer 2

hmmm, need to define it as its distance from the origin eh

Answer 3

I dont know

Answer 4

well, that is what a polar does, for some degree rotation, we are this far from the origin

Answer 5

oh

Answer 6

some identities we can apply are:

y = r sin(t)
x = r cos(t)

r^2 = x^2 + y^2

Answer 7

does this help?

Answer 8

what is that?

Answer 9

is that polar form cus I dont know

Answer 10

y^2 = 9x

x^2 + y^2 = x^2 + 9x

r^2 = r^2 cos^2(t) + 9r cos(t)

r^2 = r^2 cos^2(t) + 9r cos(t)

r^2 - r^2 cos^2(t) - 9r cos(t) = 0

(1- cos^2(t)) r^2 - (9cos(t)) r = 0

using the quadratic formula ... maybe\[r=\frac{-9cos(t)\pm\sqrt{81cos^2(t)}}{2(1-cos^2(t))}\]
\[r=\frac{-18cos(t)}{2sin^2(t)}~or~0\]

Answer 11

is that the answer if so can you explain it step by step

Answer 12

or r = -9 cot(t) csc(t)

Answer 13

i did explain it step by step :/

Answer 14

nevermind

Answer 15

Thank you

Answer 16

i prolly made some minor error that ill ahve to dbl chk ,,, but its all right there.

sub in identities and hash it out with the algebra

Answer 17

ugh, yeah, i did a -(-b) instead of a -b .... so ignore that - and it should be fine

Answer 18

@rachelmcclellan
thats might graph it and be some properties of the parabola but it does not seem to convert it a polar representation

Answer 19

Is the last answer you gave me the answer r = -9 cot(t) csc(t)

Answer 20

go thru my initial material ... i was working out a thought to refresh my memory ... ask me where it does wrong for you

Answer 21

I dont know how to do it so i wouldnt be able to tell u where u went wrong

Answer 22

all i did was use the identities to create a quadratic equation, and then solved for r. thats the best way i can approach it off the top of my head.

Answer 23

if you are not adept at quadratics ... then this question might just be too far advanced for you to accomplish

Answer 24

Change the equation to polar coordinate. y^2=9x:

amistre64 was correct in stating that rectangular coordinates can be changed to polar coordinates through the following substitutions:

x=r cos theta
y=r sin theta.

You have y^2=9x . So, from y=r sin theta, you need to obtain y^2. How?
You have 9x on the right. Just substitute r sin theta for x.

Your turn.

Answer 25

so