ElectricPavlov

Look again.......

Way to go !    See if you can do the next one......

I get the THIRD option.....see if you can figure out where you steered off-course.....

These are VERY similar to the question cphill answered a few minutes ago  ....try his methodology on these before you ask for answers....I think you should be able to do that....give it a try to see what you can find !   

f      due to  the 1/4 multiplier

g     due to the  +3

I think you want to ask for the arclength (and not the radius as you posted)

FULL circumference of a circle =  pi d   or   pi 2r

Circumference of THIS circle would then be    pi 2(8)   cm

the ARCLENGTH of 1/4 of this would be     1/4  pi   16 =    4 pi     cm

OR  maybe you meant to ask for AREA   

Area of circle = pi r ^2

   for this circle     pi (8)^2 = 64 pi cm^2

1/4 of this would be    1/4 * 64 pi =   16 pi    cm^2

Maybe a picture will help:

-2,-4  is a  POINT......the DIRECTRIX is a LINE.....  y= -6     the direct  distance between the two only involves the y distances.....

The focus was GIVEN as  -2,-4   in your question.....

Yah!   That DOES make it way easier.....did you get an  answer?