the inner and outer radii of a cylindrical pipe are 5 cm and

4cm respectively . find the area of cross section of the pipe.

Inner radius of cylindrical pipe;

*r*= 4 cm

Inner radius of cylindrical pipe;

*R*= 5 cm

Since the cross-section of cylindrical pipe is circular.

So area of cross-section of pipe = $\mathrm{\pi}\left({\mathrm{R}}^{2}-{\mathrm{r}}^{2}\right)=\frac{22}{7}\left({5}^{2}-{4}^{2}\right)=\frac{22}{7}\times 9=28.285{\mathrm{cm}}^{2}$

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