how do i find the surface area of a right cone? with the measurements of 5ft as the radus and 12ft as a hight

Question

amistre64 · Answer

do we include the base area?

amistre64 · Answer

if you cut the cone up its length and splay it out; we get a part of a circle; with radius 12 and arc length of 5

amistre64 · Answer

the total area of the circle would be 2pi(12) = 24pi

24pi/5 is the length of the arc

area of a sector is:  (radian angle)r^2/2

anonymous · Answer

thank you

amistre64 · Answer

arc length = angle(r)

5 = angle(12)

angle = 5/12 ; in radians

           5(12)^2     
area = ------- = 5(6) = 30  if I did it right :)
             12*2

amistre64 · Answer

if that includes that area of the base then add on another 25pi

anonymous · Answer

thanks