The total surface area of a cone of radius r 2 and length 2 l- isa 2 - r1-rb - r 1- r 4c - rr 1- r d 2 - r l

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Standard IX

Mathematics

Curved surface area of a Right Circular cone

The total sur...

Question

The total surface area of a cone of radius $\frac{r}{2}$ and length 2l, is
(a) 2 $π r (1 + r)$

(b) $πr (1 + \frac{r}{4})$

(c) $π r (1 + r)$

(d) 2 $π r l$

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Solution

The formula of the total surface area of a cone with base radius ‘r’ and slant height ‘l’ is given as

Total Surface Area =

Here it is given that the base radius is ‘’ and that the slant height is ‘2l’.

Substituting these values in the above equation we have

Total Surface Area =

=

Hence the correct choice is (b).

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Similar questions

Q. The total surface area of a cone whose radius is

\frac{r}{2}

and slant height 2l is
(a)

2 π r (l + r)

(b)

π r (l + \frac{r}{4})

(c)

πr (l + r)

(d)

2 π r l

Question 5
The total surface area of a cone whose radius is $\frac{r}{2}$ and slant height 2l is:

A) $2 π r (l + r)$
B) $π r (l + \frac{r}{4})$
C) $π r (l + r)$
D) $2 π r l$

Q. The Curved surface area and Total surface area of a cone having slant height

^{'} l^{'}

and base radius

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respectively are
&
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Q. Find the total surface area of a cone of radius

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and slant height

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Lateral surface area of frustum of cone =

π (r_{1} + r_{2}) l

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The total surface area of a cone of radius r2 and length 2l, is (a) 2πr (1+r) (b) πr1+r4 (c) πr (1+r) (d) 2πrl

The total surface area of a cone of radius $\frac{r}{2}$ and length 2l, is
(a) 2 $π r (1 + r)$

(b) $πr (1 + \frac{r}{4})$

(c) $π r (1 + r)$

(d) 2 $π r l$