Savitri had to make a model of a cylindrical kaleidoscope for her science project. She wanted to use chart paper to make the curved surface of the kaleidoscope. What would be the area of chart paper required by her, if she wanted to make a kaleidoscope of length 25 cm with a 3.5 cm radius? You may take π = $\frac{22}{7}$

[2 Marks]

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Solution

Radius of the base of the cylindrical kaleidoscope (r) = 3.5 cm.
Height (length) of the kaleidoscope (h) = 25 cm.
Area of chart paper required = curved surface area of the kaleidoscope
= $2 π r h = 2 \times \frac{22}{7} \times 3.5 \times 25 c m^{2} = 550 c m^{2}$
[2 Marks]

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Radius of the base of the cylindrical kaleidoscope (r) = 3.5 cm. Height (length) of the kaleidoscope (h) = 25 cm. Area of chart paper required = curved surface area of the kaleidoscope = 2πrh=2×227×3.5×25 cm2=550 cm2 [2 Marks]

Radius of the base of the cylindrical kaleidoscope (r) = 3.5 cm.
Height (length) of the kaleidoscope (h) = 25 cm.
Area of chart paper required = curved surface area of the kaleidoscope
= $2 π r h = 2 \times \frac{22}{7} \times 3.5 \times 25 c m^{2} = 550 c m^{2}$
[2 Marks]