Question

Convert the rectangular equation to a polar equation that expresses r in terms of theta

x=8

Answer 1

\[x=r \cos \theta \]

Answer 2

and \[r^2=x^2+y^2\]

Answer 3

8=rcostheta

and r^2= 8^2 + y^2 ??

Answer 4

You want r in terms of theta

Answer 5

So good, you have \[8 = r \cos \theta \] what's next

Answer 6

find y so we have sin theta ?

Answer 7

No, why would you need y, all you need is x = rcos theta, maybe I shouldn't have put the second equation.

Answer 8

or it's just 8/costheta

Answer 9

Yes, that's it

Answer 10

wow! thank you haha

Answer 11

Np

Answer 12

would you mind helping me on one more problem or at least explaining the ending to it?

Answer 13

The rectangular coordinates of a point are given. Find polar coordinates of the point such that r>0 and 0<(or equal to) theta < 2pi


(-10,10)

Answer 14

First you need to find R.. you can do that by
r2=x2+y2

Answer 15

ok and i get 0

Answer 16

:3 no
r2 = (-10)^2 + (10)^2
r^2 = 100 +100
do you see where u went wrong?

Answer 17

I didn't put parenthesis

Answer 18

r = 14.1?

Answer 19

no.. you kept the negative sign out when you were about to square..
so you got -100.. thats why you got 0.. parenthesis just reduces chance of a mistake.

Answer 20

yes

Answer 21

and that is the final answer?

Answer 22

nevermind

Answer 23

We now find tan t using the formula tan theta = y / x

Answer 24

-1

Answer 25

14.1,-1

Answer 26

you have to find the value of theta .. whatever is theta..
that would be your other coordinate..

Answer 27

-1 is not the coordinate for theta?

Answer 28

no.. its not theta..
its tan theta =-1
take inverse of tang.. and keep in mind that in which quadrant tan is negative.

Answer 29

-45

Answer 30

tan is negative in second quadrant.. and the angle there is between 90 and 180 so theta would be in between here.

Answer 31

this would be your theta

Answer 32

150 degrees

Answer 33

how did u got 150?

Answer 34

well you got -45.. so subtract it from 180
=180-45
change it into radian.. that would be your other coordinate

Answer 35

how do i post a question