Question

find polar coordinates for three different points that line on the graph of the equation r=-4cosθ. I have (-4,0) but i can't find the other two.

Answer 1

plugin \(\theta = \dfrac{\pi}{2}\), you get \(r = -4\cos(\dfrac{\pi}{2}) = -4*0 = 0\)

so (0, pi/2) is another point on the given graph

Answer 2

similarly see if you can find another point by plugging in \(\large \theta = \dfrac{\pi}{6}\)

Answer 3

almost -4 (3.999) so the next point would be (-4, pi/6)?

Answer 4

doesn't look correct

Answer 5

\(r = -4\cos(\theta)\)

plugin \(\theta = \dfrac{\pi}{6}\)

\(r = -4\cos(\dfrac{\pi}{6}) = -4*\dfrac{1}{2} = -2\)

so (-2, pi/6) is another point on the graph

Answer 6

had the calculator in degree mode...

Answer 7

you're using the unit circle aren't you?

Answer 8

cos(pi/3)= 1/2...

Answer 9

thank you

Answer 10

thats it!