# Thread: cartesian and polar coordinate question

1. ## cartesian and polar coordinate question

question is: Find the Cartesian coordinates corresponding to (4 pi/6) and polar coordinates corresponding to (-3, sqrt(3) )

i've attached some work to the problem,

ImageShack - Hosting :: untitledui2.png

however, is the tan-theta the answer then?
also, i'm confused where the 5pi/6 came from?

what part is where i can stop? which part is the answer?

thanks

2. Originally Posted by rcmango
question is: Find the Cartesian coordinates corresponding to (4 pi/6) and polar coordinates corresponding to (-3, sqrt(3) )

i've attached some work to the problem,

ImageShack - Hosting :: untitledui2.png

however, is the tan-theta the answer then?
also, i'm confused where the 5pi/6 came from?

what part is where i can stop? which part is the answer?

thanks
The first problem is correct.

For the second, consider
tan(theta) = sqrt{3}/3

What angle (theta) is this? (theta) = (pi)/6 rad.

But we need (theta) for tan(theta) = -sqrt{3}/3. The reference angle is (pi)/6 rad and tangent is negative in QII. So (theta) = (pi) - (pi)/6 = 5(pi)/6 rad.

-Dan