Answer:
Planet Ruba has 900,000 more aliens
Step-by-step explanation:
Please kindly see the attached file for more explanation
Realize the tangent function has a period of 180°, so when your calculator (or memory) tells you
.. θ = arctan(-1)
.. θ = -45°
you can translate that value into the desired range by adding multiples of 180° to get the two solutions ...
.. θ = 135°
.. θ = 315°