Thread: rectangular to polar equation

convert the rectangular to a polar equation:

-8x-3y+5=0

i know that x= r cos theta, as well as other identities

convert the polar to a rectangular equation:
r= 2/ (4-5 cos theta)

i don't even know where to begin here!

thanks

Originally Posted by ss103

convert the rectangular to a polar equation:

-8x-3y+5=0

i know that x= r cos theta, as well as other identities

Mr F says: Then substitute them into the equation and solve for r.

convert the polar to a rectangular equation:
r= 2/ (4-5 cos theta)

i don't even know where to begin here!

thanks

.

Now square both sides and substitute . Re-arrange into a standard form (looks like it might be a hyperbola).

thanks!

but for the first one, i tried to solve it but i dont know how:

-8r cos theta - 3r sin theta +5 =0
where do i go now? do i square it?

Originally Posted by ss103

thanks!

but for the first one, i tried to solve it but i dont know how:

-8r cos theta - 3r sin theta +5 =0
where do i go now? do i square it?

=> 8r cos theta + 3r sin theta = 5

=> r (8 cos theta + 3 sin theta) = 5

etc.