Surface area of cone is a sum of surface of its base and surface of its mantle.
Surface of its base is a circle which surface we will calculate like this:
Sb = pi*r^2 where r is d/2
Sb = 201m^2
Surface of mantle we calculate by:
Sm = pi*l*r where l is length of side of cone.
l =

= 25.3
Sm = 635.8m^2
Total suface is:
Sb + Sm = 836.8m^2
Do it both side +5 . Then that 23 will be 28.so the question will be 4a=28.
then diveded by 4 both side.
A will be 7.
Your answer is "7"
28÷4=7 ^^
Five Hundred is in word form to put it in standard notation, we just write he number like so 500.