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In a triangle AOB, R and Q are the poin...

In a triangle AOB, R and Q are the points on the side OB and AB respectively such that 3OR = 2RB and 2AQ = 3QB. Let OQ and AR intersect at the point P (where O is origin).
Q. If the point P divides OQ in the ratio of `mu:1`, then `mu` is :

A

`(2)/(19)`

B

`(2)/(17)`

C

`(2)/(15)`

D

`(10)/(9)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the ratio \( \mu:1 \) in which point \( P \) divides line segment \( OQ \). We will use the concept of section formula and vector representation. ### Step-by-Step Solution: 1. **Understanding the Triangle and Points**: - Let \( O \) be the origin, \( A \) and \( B \) be points in the plane. - Let \( R \) be a point on line segment \( OB \) such that \( 3OR = 2RB \). - Let \( Q \) be a point on line segment \( AB \) such that \( 2AQ = 3QB \). 2. **Finding the Position Vector of \( R \)**: - Since \( R \) divides \( OB \) in the ratio \( 2:3 \), we can use the section formula: \[ \vec{R} = \frac{3\vec{O} + 2\vec{B}}{3 + 2} = \frac{3\vec{0} + 2\vec{B}}{5} = \frac{2\vec{B}}{5} \] 3. **Finding the Position Vector of \( Q \)**: - Since \( Q \) divides \( AB \) in the ratio \( 3:2 \), we can again use the section formula: \[ \vec{Q} = \frac{2\vec{A} + 3\vec{B}}{2 + 3} = \frac{2\vec{A} + 3\vec{B}}{5} \] 4. **Finding the Position Vector of \( P \)**: - Let \( P \) divide \( OQ \) in the ratio \( \mu:1 \). By the section formula: \[ \vec{P} = \frac{\mu \vec{Q} + 1 \cdot \vec{O}}{\mu + 1} = \frac{\mu \vec{Q}}{\mu + 1} \] - Substituting \( \vec{Q} \): \[ \vec{P} = \frac{\mu \left(\frac{2\vec{A} + 3\vec{B}}{5}\right)}{\mu + 1} = \frac{2\mu \vec{A} + 3\mu \vec{B}}{5(\mu + 1)} \] 5. **Finding the Position Vector of \( P \) Using \( AR \)**: - Now, we also need to express \( P \) in terms of \( A \) and \( R \). Let \( P \) divide \( AR \) in some ratio \( k:1 \): \[ \vec{P} = \frac{k\vec{R} + 1\vec{A}}{k + 1} \] - Substituting \( \vec{R} \): \[ \vec{P} = \frac{k\left(\frac{2\vec{B}}{5}\right) + \vec{A}}{k + 1} = \frac{\frac{2k\vec{B}}{5} + \vec{A}}{k + 1} \] 6. **Equating the Two Expressions for \( \vec{P} \)**: - We have two expressions for \( \vec{P} \): \[ \frac{2\mu \vec{A} + 3\mu \vec{B}}{5(\mu + 1)} = \frac{\frac{2k\vec{B}}{5} + \vec{A}}{k + 1} \] - Cross-multiplying gives: \[ (2\mu \vec{A} + 3\mu \vec{B})(k + 1) = (2k\vec{B} + 5\vec{A})(\mu + 1) \] 7. **Expanding and Rearranging**: - Expanding both sides: \[ 2\mu k \vec{A} + 2\mu \vec{A} + 3\mu k \vec{B} + 3\mu \vec{B} = 2k\mu \vec{B} + 5\mu \vec{A} + 2k\vec{B} + 5\vec{A} \] - Rearranging gives us a system of equations. 8. **Solving for \( \mu \)**: - By equating coefficients of \( \vec{A} \) and \( \vec{B} \), we can solve for \( \mu \) and \( k \). - After simplification, we find: \[ \mu = \frac{10}{9} \] ### Final Answer: Thus, the value of \( \mu \) is \( \frac{10}{9} \).
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