Convert the Cartesian coordinate (-1,2) to polar coordinates, 0≤θ<2π

Question

I know r is sqrt(5) but how would I find theta between 0 and 2pi?
Thanks in advance!

Answer 1

you know that the point is in quad II and
tanØ = 2/-1

I know that for tanØ= +2, Ø = appr 1.107
so our angle in II is Ø = π-1.107 = 2.0344

so it has to be (5, 2.0344) if you use the form (r,Ø)

Answer 2

I see thanks for the help! I forgot to put my calculator on radian mode and got a totally different answer!