aa

[cerulean hound]

is the ans 1712 mm^2 ??

[ebon valley]

no it was not

@cerulean hound

[cerulean hound]

2419 mm^2 ??

@ebon valley

If not this what it is?

[ebon valley]

yes i think it was that

[cerulean hound]

hmm

just subtract the csa of smaller cone from larger cone

and as we have removed the smaller cone

the upper part of frustum is also counted as surface so the lower the part

pi×5×5=area of upper exposed part
pi×15×15=area of lower exposed part