How do you write the polar coordinates for the point with rectangular coordinates (0, 3)?

1 Answer
Nov 6, 2015

(3,90^\circ)(3,90)

Explanation:

Polar coordinates are in the form (r,theta)(r,θ)

First we need to find the vector, it goes from the origin (0,0)(0,0) to your point (0,3)(0,3).

\vec{u}=<0\hat{i}+3\hat{j}> - <0\hat{i}+0\hat{j}> = 0\hat{i} + 3\hat{j}=3\hat{j}u=<0ˆi+3ˆj><0ˆi+0ˆj>=0ˆi+3ˆj=3ˆj

You can see the vector goes straight up, just in the yy direction, so the angle is 90^\circ90 and the radius rr is 3. Let's prove that.

As we said, your vector \vec{u}=3\hat{j}u=3ˆj. Let's find the modulus (radius) of the vector:

r=|\vec{u}|=\sqrt{3^2}=3r=u=32=3

And the angle will be:

theta =arctan(3/0)=90^\circθ=arctan(30)=90