# COnverting rectangular equations to polar (and vice versa)

• Apr 27th 2008, 11:28 PM
cjmac87
COnverting rectangular equations to polar (and vice versa)
i understand the concepts of converting single coordinates, however im confused on how and why on some these parts.... hopfully i could get a little more help on this...

Convert equations to rect.

r=4

$\displaystyle rsin(\theta) = -2$

$\displaystyle \theta = pi/3$

$\displaystyle r = sin(\theta) - cos (\theta)$

Convert Equations to polar

$\displaystyle 2x^2 + 2y^2 = 3$
$\displaystyle y = 3$

I already got a hang of some of the basics of this... but a little further explanation owuld be much appreciated so i can hopeuflly ace this coming quiz. ty
• Apr 27th 2008, 11:49 PM
the relation between polar and rectangle:

$\displaystyle x = r \cos (\theta)$
$\displaystyle y = r \sin (\theta)$
$\displaystyle r^2 = x^2 + y^2$

for example:

$\displaystyle 2x^2 + 2y^2 = 3$
$\displaystyle 2(x^2 + y^2) = 3$
$\displaystyle 2r = 3$
$\displaystyle r=\frac {3}{2}$

• Apr 28th 2008, 12:22 AM
Jameson
• Apr 28th 2008, 08:06 AM
cjmac87
ok, this is more of the material my teacher wants.... can anyone please check on correctness and help me fix my errors.

http://www.mathhelpforum.com/math-he...cbb1b055-1.gif : y=1.732x using tan(y/x)

http://www.mathhelpforum.com/math-he...59ab9552-1.gif : $\displaystyle r^2 = y^2 - x^2$

$\displaystyle rsec(\theta) = -4$

-4 = x

$\displaystyle r = cos(\theta)$

y=x

Convert Equations to polar

http://www.mathhelpforum.com/math-he...639a02fc-1.gif ===>$\displaystyle 2cos(\theta)^2 + 2sin(\theta)^2 = 3$

please tell me whats right, whats right, and what i can fix.

$\displaystyle y = -3 \longrightarrow sin^2 = - 3$