How do you convert #(7sqrt3, -7) # into polar coordinates?

1 Answer
Jul 28, 2016

#(7sqrt3,-7)to(14,-pi/6)#

Explanation:

To convert from #color(blue)"cartesian to polar coordinates"#

That is #(x,y)to(r,theta)#

#color(orange)"Reminder"#

#color(red)(|bar(ul(color(white)(a/a)color(black)(r=sqrt(x^2+y^2))color(white)(a/a)|)))#

#color(red)(|bar(ul(color(white)(a/a)color(black)(theta=tan^-1(y/x))color(white)(a/a)|)))#

here #x=7sqrt3" and " y=-7#

#r=sqrt((7sqrt3)^2+(-7)^2)=sqrt(147+49)=sqrt196=14#

Now #(7sqrt3,-7)# is in the 4th quadrant and care must be taken to ensure #theta# is in the 4th quadrant.

#theta=tan^-1(-7/(7sqrt3))=tan^-1(-1/sqrt3)=-pi/6" 4th quadrant"#

#rArr(7sqrt3,-7)=(14,-pi/6)=(14,-30^@)#