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The region R

The outer circle has the radius of 2n+6

The inner circle has radius n-1


The area of R is greater than the area of a circle of radius n+13


n is an integer


Find the least possible value of n

User Jehof
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1 Answer

4 votes

Answer:

We can start by using the formula for the area of a circle: A = πr^2.

The area of the outer circle is greater than the area of a circle of radius n+13, meaning that:

π(2n+6)^2 > π(n+13)^2

The area of the inner circle is:

π(n-1)^2

The area of the region R is the area of the outer circle minus the area of the inner circle:

π(2n+6)^2 - π(n-1)^2 > π(n+13)^2

Now we can simplify and solve the inequality:

8n^2 + 96n + 72 > n^2 + 26n + 169

7n^2 + 70n - 97 > 0

(n-1)(7n+97) > 0

n > 1

The least possible value of n is 2, since n must be an integer, n=1 doesn't meet the requirement of the problem statement.

So the least possible value for n is 2.

Explanation:

User Cpchung
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