the area between a concentric circle is 1540cm². If the radius of the outer circle is 21 cm, calculate the radius of the inner circle
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Answer:
Correct Question:
The area enclosed between the concentric circles is 770 cm². If the radius of the outer circle is 21 cm, find the radius of the inner circle.
Answer:
The radius of the inner circle is 14 cm.
Step-by-step explanation:
Given that:
The area between a concentric circle is 770 cm².
The radius of the outer circle is 21 cm.
To Find:
The radius of the inner circle.
Let us assume:
The radius of the inner circle be x.
Formula:
Area between a concentric circle = π(R² – r²)
Where,
R = The radius of the outer circle
r = The radius of the inner circle
Finding the radius of the inner circle:
According to the question.
⟶ π(21² – x²) = 770
⟶ π(441 – x²) = 770
⟶ 441 – x² = 770/π
⟶ 441 – x² = (770 × 7)/22
⟶ 441 – x² = 245
⟶ x² = 441 – 245
⟶ x² = 196
⟶ x = √196
⟶ x = 14
∴ The radius of the inner circle = 14 cm
[tex]{\textsf{\textbf{\underline{\underline{∴ The radius of the inner circle = 14 cm\::}}}}} \\ [/tex]
correct Question:
Step-by-step explanation:
Given that:
To Find:
Let us assume:
Formulas used:
Where,
Finding the radius of the inner circle:
According to the question.
⟶ π(21² – x²) = 770
⟶ π(441 – x²) = 770
⟶ 441 – x² = 770/π
⟶ 441 – x² = (770 × 7)/22
⟶ 441 – x² = 245
⟶ x² = 441 – 245
⟶ x² = 196
⟶ x = √196
⟶ x = 14
[tex]\small{\textsf{\textbf{\underline{\underline{∴ The radius of the inner circle = 14 cm\::}}}}} \\ [/tex]