Find the amount of sheet metal needed to form a conical funnel of base radius 30 cm and vertical height 50 cm, allowing for a 0.5 cm overlap at the join.

Answer 1

The lateral surface area is

a = 2πrs = 2πr√(r^2+h^2)
= 2π*30*√3400
= 600π√34

Assuming that the join is 0.5 cm at the base, but decreases approaching the point of the cone, the 0.5cm overlap at the base means that you have a portion of the surface area added. That amount is

0.5/(2π*30) = 1/(120π)

of the surface area. So, add an additional

1/(120π) * 600π√34 = 5√34 cm^2

Answer 2

Omg so easy do in grade 5 india JEE