Question

Find the area of Circular Ring if outer diameter D= 38mm, inner diameter d=32mm *

4 points

330mm²

340mm²

334mm²

331mm²​

Answer 1

$\underline { \blue { Dimensions \:of \: a\:Ring :}}$

$Outer \: diameter (D) = 38 \:mm$

$Outer \: radius (R)= \frac{D}{2} \\= \frac{38}{2}\\= 19 \:mm$

$Inner \: diameter (d) = 32 \:mm$

$Inner \: radius (r) \\= \frac{d}{2} \\= \frac{32}{2}\\= 16 \:mm$

$\red{ Area \: of \: circular \:ring } \\= \pi ( R^{2} - r^{2} ) \\= \pi ( R + r )( R - r ) \\= \pi ( 19 + 16 )( 19 - 16 ) \\= \frac{22}{7} \times 35 \times 3 \\= 22 \times 5 \times 3 \\= 330 \: mm^{2}$

Therefore.,

$\red{ Area \: of \: the \:circular \:ring }\green { = 330 \: mm^{2}}$

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