Question

a joker cap is in the form of a right circular cone of base radius 7cm and height 27 cm.find the area of the sheet required to make 10 such caps

Answer 1

You need to find the LSA of the cone which gives you the answer:
πrl
l²=r²+h²
=7²+27²
=49+729
=778
l=28(approx)
πrl
=3.14×7×28
=615.4

Area of sheet required to make 10 such caps
=615.4×10
=6154(approximately)

Answer 2

l²=r²+h²
l=√7²+27²
l=√49+729
l=√778
C.S.A=πrl
C.S.A=(22/7)×7×√778
C.S.A=613.63
AREA OF SHEET REQUIRED TO MAKE 10 CAPS=613.63×10
 AREA OF SHEET REQUIRED TO MAKE 10 CAPS=6136.3cm² (its accurate)