Verified answer

NB : it's a +1 and not - 1

well, "rectangular form" ... i have never heard this before...

...G says it may be cartesian (from René Descartes) coordinates...

so the point M of polar coordinates is the radius r > 0 and the argument theta :

so (r , theta) = ( +1 , 5pi/6)

is positioned so that :

vector(OM) = r cos(theta) i + r sin(theta) j ( i and j unit vectors of x and y-axis)

= 1 cos5pi/6 . i + 1 sin5pi/6 . j

= -√3/2 i + (1/2) j

therefore the cartesian coordinates of M are : M ( -√3/2 ; 1/2)

et voilà !!

hope it' ll help !!

false. it should be (√3/2, -1/2)