Answer:
1533.88261311522
Step-by-step explanation:
Let r be the radius of the (base/circle)
and L be the slant height of the cone
Formula ………………………………………………………………………………………………………
The surface area of a cone = the (curved/lateral) surface area + the base
[tex]=\pi r^{2}\ \ \ +\ \ \ \pi Lr[/tex]
=========================================
[tex]r=\frac{21}{2} =10.5[/tex]
L = BC = 36
[tex]\text{surface area} =\pi \left( 10.5\right)^{2} +\pi \times 36\times \left( 10.5\right)[/tex]
[tex]=346.360590058275 + 1187.52202305694[/tex]
[tex]=1533.88261311522[/tex]
