Question

Find the rectangular coordinates of the point with the polar coordinates. (-7, 2pi/3)?

I think its (7/2, -7sqrt3/2) ??

Answer 1

given a polar (r,a)

the cartesian is: (r cosa , r sina)

Answer 2

-7 is an odd construct tho ... valid; but odd

turning 2pi/3 and backing up by 7 is the same: (2-3)pi/3 = -pi/3

60 under x

Answer 3

pfft, pictures off

Answer 4

\[\frac{2\cancel{\pi}~~180}{3~~~~\cancel{\pi}}\]
\[2(60)=120\]
\[120-180=-60^o\]

Answer 5

..... i have no clue what you just did :(

Answer 6

you are correct

Answer 7

i was trying to find the appropriate angle is all....

(-7,rad) is an odd construct; you have to move backwards to get to the terminal point is all

Answer 8

yeah normally r is positive...a neg "r" adds pi to the angle

Answer 9

its best to use (7,a-pi)

Answer 10

add or subtract:)

Answer 11

right either 1 works

Answer 12

you end up in the 4th quad as a result which means your x and y are going to have negative values ... so unless theres a typo your results were in error

Answer 13

opps, im in error now

Answer 14

+x,-y in Q4

Answer 15

im so confused guys lol..

Answer 16

the outcome is still valid for: x = r cosa, y=r sina

Answer 17

-7 cos(2pi/3) = 7/2

-7 sin(2pi/3) = -7sqrt(3)/2

Answer 18

okay thankyou lol(:

Answer 19

:) good luck