The equation of a circle is (x-20)^2 + (y-.05)^2=81. what is the radius

The radius is 9 units.

Step-by-step explanation:

As the equation for circle is (x-a)² + (y-b)² = r² where r reoresents the radius of circle :

r² = 81

r = √81

= 9 units

18

step-by-step explanation:

draw the shape and you will see that f and k are actually at adjacent vertices (points of the hexagon that are neighboring).   so find the distance between (1,2) and (4,2).   that is easy since (1,2) and (4,2) is just a vertical distance to count, which is 3.   it is a regular polygon which means all sides are congruent.   you have 6 sides (hexa) so multiply 6 by 3 to receive 18.