Question

when r = 30 cm and s = 80 cm.
Find the surface area of the ENTIRE cone shown here please

Answer 1

find the height 'h' first!
using pythagoras theorem

Answer 2

ok , will do this now

Answer 3

h = \(\sqrt {80^2-30^2}\)

Answer 4

or you can directly use the formula
\(\large A = \pi r(r+s)\)

Answer 5

yes so h= 85.44 or \[10\sqrt{73}\]

Answer 6

and for area ?

Answer 7

how come h is greater than 80 ?

Answer 8

sorry my bad h= 74.161
and
A= 3.14 x 30 (30+80) = 10362 square cm

Answer 9

\(s^2=h^2+r^2\)
and i got 10367 using the google calculator...
u have choices ?

Answer 10

is this correct ?

Answer 11

yes the choices are

A) 10,306 square centimeters
B) 10,362 square centimeters
C) 11,362 square centimeters
D) 12,306 square centimeters

Answer 12

yes, then 10362 is correct :)

Answer 13

so its B
thanks a lot @hartnn for your help :)

Answer 14

welcome ^_^