Question 1053025
For 0-5i, plot point P(0,-5),
with the real part as the x-coordinate,
and the imaginary part as the y-coordinate.
{{{r=5}}} is the distance to the origin, O(0,0).
{{{theta=270^o}}} (or {{{theta=3pi/2}}} in radians) is the angle OP forms with the positive x-axis,
measured counterclockwise from the positive x-axis.
{{{drawing(300,300,-6,6,-6,6,
grid(0),circle(0,-5,0.1),locate(0.1,-4.7,P(0,-5)),
red(arc(0,0,6.8,6.8,90,360)),
circle(0,0,0.1),locate(0.1,0.65,O(0,0)),
red(triangle(0,-3.4,-0.3,-3.2,-0.3,-3.6)),
locate(-2.7,2.18,red(theta=270^o)),line(0,0,0,-5),
arrow(0,0,0,-5),arrow(0,-5,0,0),locate(0.1,-2,r=5)
)}}}