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Two equal chords AB and AC of the circle...

Two equal chords AB and AC of the circle `x^2 +y^2-6x -8y-24 = 0` are drawn from the point `A(sqrt33 +3,0)`. Another chord PQ is drawn intersecting AB and AC at points R and S, respectively given that `AR=SC=7` and RB = AS = 3 . The value of `PR`/`QS` is

A

1

B

1.5

C

2

D

None of these

Text Solution

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The correct Answer is:
To solve the problem, we will follow these steps: ### Step 1: Rewrite the equation of the circle The given equation of the circle is: \[ x^2 + y^2 - 6x - 8y - 24 = 0 \] We can rewrite this in standard form by completing the square. ### Step 2: Completing the square 1. For \(x\): \[ x^2 - 6x \rightarrow (x - 3)^2 - 9 \] 2. For \(y\): \[ y^2 - 8y \rightarrow (y - 4)^2 - 16 \] Now substituting back into the equation: \[ (x - 3)^2 - 9 + (y - 4)^2 - 16 - 24 = 0 \] This simplifies to: \[ (x - 3)^2 + (y - 4)^2 = 49 \] Thus, the center of the circle is \( (3, 4) \) and the radius is \( 7 \). ### Step 3: Identify point A The point \( A \) is given as \( (\sqrt{33} + 3, 0) \). We need to check if this point lies on the circle: 1. Substitute \( x = \sqrt{33} + 3 \) and \( y = 0 \) into the circle's equation: \[ (\sqrt{33} + 3 - 3)^2 + (0 - 4)^2 = 49 \] \[ (\sqrt{33})^2 + 16 = 49 \] \[ 33 + 16 = 49 \] This confirms that point A lies on the circle. ### Step 4: Set up the segments Given: - \( AR = SC = 7 \) - \( RB = AS = 3 \) ### Step 5: Calculate lengths From the segments: - \( AB = AR + RB = 7 + 3 = 10 \) - \( AC = AS + SC = 3 + 7 = 10 \) Since \( AB = AC \), both chords are equal. ### Step 6: Use the power of a point theorem According to the power of a point theorem: \[ PR \cdot RQ = AR \cdot RB \] Let \( PR = x \) and \( RQ = y \). Then: \[ x \cdot y = 7 \cdot 3 = 21 \] ### Step 7: Set up the second chord For chord \( PQ \): \[ QS \cdot SP = AS \cdot SC \] Let \( QS = a \) and \( SP = b \). Then: \[ a \cdot b = 3 \cdot 7 = 21 \] ### Step 8: Find the ratio We need to find the ratio: \[ \frac{PR}{QS} = \frac{x}{a} \] From the previous steps, we know: \[ x \cdot y = 21 \quad \text{and} \quad a \cdot b = 21 \] Thus, \( PR \cdot RQ = QS \cdot SP \). Since both products equal 21, we can deduce: \[ \frac{PR}{QS} = 1 \] ### Final Answer The value of \( \frac{PR}{QS} \) is \( 1 \). ---

To solve the problem, we will follow these steps: ### Step 1: Rewrite the equation of the circle The given equation of the circle is: \[ x^2 + y^2 - 6x - 8y - 24 = 0 \] We can rewrite this in standard form by completing the square. ### Step 2: Completing the square ...
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