Respuesta :

Polar coordinates : r= - 5, α= - 180⁰.
Rectangular coordinates : 
x=r*cosα = (-5)*cos (-180⁰)=(-5)*(-1)=5
y=r*sinα = (-5)*sin(-180⁰)=(-5)*0=0

So, (-5, -180°) (polar coordinates) is the same as (5,0) (rectangular coordinates).