Question

In polar representation of a complex number (r, 2π) lies on ____________

(a) x-axis

(b) y-axis

(c) z-axis

(d) any axis

The question was posed to me during an interview.

Enquiry is from Argand Plane and Polar Representation in section Complex Numbers and Quadratic Equations of Mathematics – Class 11

Answer 1

Right option is (a) x-axis

Easiest explanation: To convert polar representation (r, θ) into argand plane (x, y), substitute x = r cos θ and y = r sin θ.

x = r cos 2π = r and y = r sin 2π = 0.

Argand plane representation is (r, 0). Since imaginary part is zero, so it lies on real axis i.e. x-axis.