Question

Find the rectangular coordinates of (-3, 120 degrees)

Answer 1

-3 cos120 deg and -3sin120 deg

Answer 2

(r,theta) ==> ( r*cos(theta), r*sin(theta) )

Answer 3

I can get that far I'm just not sure what to do next

Answer 4

that's it, that is an ordered pair of numbers in cartesian

Answer 5

r = -3, as far as the \(\theta\) value is \(120^o\)

Answer 6

you can simplify cos(120) and sin(120)

Answer 7

how do you simplify?

Answer 8

do you know the unit circle?

Answer 9

A little bit, but not very well

Answer 10

you should know cos(120) if they are having you convert from polar to rectangular...

Answer 11

so, if you say want an (x,y) find "x" by

x = -3(cos(120))

so, what's the cosine of 120 degrees?

Answer 12

one second.

Answer 13

http://www.youtube.com/watch?v=OBmhgiLi77k

Answer 14

in the end, you get a "number" for x and for y, and you plug those right back in an ordered pair (x,y), they'll just be rectangular, and not polar anymore

Answer 15

go to that lnk, watch and learn it, it is a must for this stuff:)

Answer 16

K thanks