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"Area a Oof a Circular Ring Formed by 2 Concentric Circles is Equal to the Product of Pie and the Difference of the Square of the Bigger Radius R and the Square of the Bigger Radius R and the Square - Mathematics

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प्रश्न

"Area A oof a circular ring formed by 2 concentric circles is equal to the product of pie and the difference of the square of the bigger radius R and the square of the bigger radius R and the square of the smaller radius r. Express the above statement as a formula. Make r the subject of the formula and find r, when A = 88 sq cm and R = 8cm.

योग

उत्तर

Radius of bigger circle = R
Radius of smaller circle = r

Area = A = π(R2 - r2)

⇒ A = π(R2 - r2)

⇒ `"A"/pi = "R"^2 - "r"^2`

⇒ r2 = `"R"^2 - "A"/pi`

⇒ r = `sqrt("R"^2 - "A"/pi)`

Putting A = 88cm2 and R = 8cm

⇒ r = `sqrt(8^2 - 88/(22/7)`
= 6cm.

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Changing the Subject of a Formula
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 6: Changing the subject of a formula - Exercise 6.3

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फ्रैंक Mathematics [English] Class 9 ICSE
अध्याय 6 Changing the subject of a formula
Exercise 6.3 | Q 20
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