What is the polar form of ( -5,-1 )?

1 Answer
Jan 3, 2016

(sqrt26,arctan(1/5) - pi)

Explanation:

Let A(-5,-1).The polar form will be something like (r,theta) with r non-negative and theta in [0,2pi].

The module will be given by the norm of the vector OA which is sqrt((-5)^2 + (-1)^2) = sqrt26.

The angle between the (Ox) axis and the vector OA will be given by arctan(y/x) - pi = arctan((-1)/(-5)) - pi = arctan(1/5) - pi (we substract pi because x < 0 and y < 0, and it will give us the principal measure of the angle ie the angle in ]-pi,pi]).