Question

the diameter of a circular Park is 84 M 3.5 M Wide Road runs on the outside around it find the cost of constructing the road at rupees 200 per metre square​

Answer 1

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$radius \: of \: a \: circular \: park = ( \frac{84}{2} )m \: = 42m.$

$width \: of \: the \: road \: = 3.5m$

$radius \: of \: the \: outer \: circle = (42 + 3.5)m$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 45.5m \: .$

Area of the road

= ( area of outer road ) - ( area of inner road )

= {π × ( 45.5 )² - π × ( 42 )² } m²

= π × {( 45.5 )² - (42)² } m²

= { π × ( 45.5 + 42 ) × ( 45.5 - 42 )} m²

$= ( \: { \frac{22}{7} \times 87.5 \times 3.5)m }^{2}$

$= {962.5 \: m}^{2}$

Answer 2

for 200 rs per meter then

200 × 84

16800 rs is the answer