Question

Write the polar equation in rectangular form.

r cos theta=5

Answer 1

z=a+jb

Answer 2

eh?

Answer 3

\[x^2 + y^2 = r^2\]
\[\tan \theta = \frac{y}{x}\]
Note also identity:
\[\sec^2 \theta = 1 + \tan^2 \theta\]

Answer 4

rewrite equation
\[r = 5 \sec \theta\]
square both sides
\[r^2 = 25 \sec^2 \theta\]
substitute
\[x^2 +y^2 = 25(1 + \frac{y^2}{x^2})\]

Answer 5

You lost me...

Answer 6

which part

Answer 7

How did you end up with tan?

Answer 8

In order to get r isolated, you divided both sides by cos theta, correct?

Answer 9

from the identity
sec^2 = 1 +tan^2

Answer 10

yes

Answer 11

that would have given us \[\frac{5}{cos \theta}\]which is also...what?

Answer 12

Wait...it's also sec -_-

Answer 13

so that's how you got 5sec...

I gotchya now ;)

Answer 14

wait hold on ... i forgot something
i made this harder than it really is

\[x = rcos \theta\]
\[y = r \sin \theta\]

all you have to do is sub in "x" for rcos .... leaving
\[x = 5\]

Answer 15

lol

I got what you meant in the end after I went through it XD

Answer 16

ok good :)

Answer 17

Thank you very much (: