Question

The shaded portion is cut out from the circle, and then the remaining portion is folded to make a
cone. Now, if the bottom of the cone is covered with paper to form the base, what will be the ratio
of the area of original circle to the total surface area of the cone made?​

Answer 1

the total surface area of any cone is

$\pi \: r(l + r)$

where r is the radius and l is the slant height of the cone.

When the shaded portion is cut out from the circle and remaining portion is folded to make a cone. Then we need to calculate the total surface area of the cone with the general formula of the cone.

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Answer 2

The total surface area of a cone is the combination of the curved surface as well as the base area of a cone.

The formula to calculate the total surface area of the cone is:

TSA of cone =( πr2 + πrl )

                    = πr(l+r) square units.

where r = the radius

l = the slant height of the cone.

According the question,when the shaded portion is cut out from the circle and remaining portion is folded to make a cone.

In that case we need to calculate the total surface area of the cone with the general formula of the cone.

#SPJ3