state the polar form of complex numbers?

Answer 1

If you have a complex number a + bi, the polar form is calculated as follows:

r = √(a² + b²)
θ = arctan(b/a)

With θ, you have to be careful; if a is negative:

θ = π + arctan(b/a)

bag o' hot air is right; I fixed it.

Answer 2

The answer above is mostly correct, but it should read that for the case where a < 0 there should be a plus sign instead of the minus sign:

theta = pi + arctan(b/a).

Plus if a = 0 then theta is pi/2 if b > 0 and -pi/2 if b < 0. If both a and b are zero, then it doesn't matter what theta is since r = 0. Cheers!