# Ex.13.2 Q6 Surface Areas and Volumes - NCERT Maths Class 9

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## Question

Curved surface area of a right circular cylinder is $$4.4$$ \begin{align}\rm{{m^2}}. \end{align}. If the radius of the base of the cylinder is $$0.7 \,\rm{m},$$ find its height.

Video Solution
Surface Areas And Volumes
Ex 13.2 | Question 6

## Text Solution

Reasoning:

The curved surface area of a right circular cylinder of the base radius $$r$$ and height  $$h$$  is \begin{align}2\pi rh. \end{align}

What is the known?

Curve surface area and radius of the base.

What is the unknown?

Height of the cylinder.

Steps:

Curved surface area \begin{align}2\pi rh \end{align}$$=$$ $$4.4$$\begin{align}\rm{{m^2}} \end{align}

\begin{align}\rm radius(r) &= 0.7m\\\rm height(h) &= ? \end{align}

\begin{align}2\pi rh &= 4.4\\2 \times \frac{{22}}{7} \times 0.7 \times h &= 4.4\\h &= \frac{{4.4 \times 7}}{{2 \times 22 \times 0.7}}\\\,\,\,\,\, &= 1\,\,\rm{m} \end{align}

The height of the right circular cylinder is \begin{align} = 1\,\rm{m} \end{align}.

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