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If AD is median of triangle ABC and P is...

If AD is median of triangle ABC and P is a point on AC such that area `(DeltaADP) : area (Delta ABD) = 2 :3.`, then area `(DeltaPDC) : area (DeltaABC)` is equal to:

A

`1 : 5`

B

`5 : 1`

C

`1 :6`

D

`6 : 1`

Text Solution

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To solve the problem, we need to find the ratio of the area of triangle PDC to the area of triangle ABC given that AD is a median of triangle ABC and the ratio of the areas of triangles ADP and ABD is 2:3. ### Step-by-Step Solution: 1. **Understanding the Triangle and Median**: - Let triangle ABC have a median AD. This means that D is the midpoint of side BC. - Therefore, the area of triangle ABD is equal to the area of triangle ADC. 2. **Setting Up the Areas**: - Let the area of triangle ABD be denoted as \( S \). - Since AD is a median, the area of triangle ADC is also \( S \). - The total area of triangle ABC is \( 2S \) (since \( Area(ABC) = Area(ABD) + Area(ADC) \)). 3. **Using the Given Ratio**: - We know from the problem statement that: \[ \frac{Area(ADP)}{Area(ABD)} = \frac{2}{3} \] - Let the area of triangle ADP be \( A_{ADP} \). Then: \[ A_{ADP} = \frac{2}{3} \cdot S \] 4. **Finding the Area of Triangle PDC**: - The area of triangle ABD can be expressed as: \[ Area(ABD) = Area(ADP) + Area(PDC) \] - Therefore, we can write: \[ S = A_{ADP} + Area(PDC) \] - Substituting \( A_{ADP} \): \[ S = \frac{2}{3}S + Area(PDC) \] - Rearranging gives: \[ Area(PDC) = S - \frac{2}{3}S = \frac{1}{3}S \] 5. **Finding the Ratio of Areas**: - Now we need to find the ratio of the area of triangle PDC to the area of triangle ABC: \[ \frac{Area(PDC)}{Area(ABC)} = \frac{\frac{1}{3}S}{2S} = \frac{1}{3} \cdot \frac{1}{2} = \frac{1}{6} \] ### Conclusion: The ratio of the area of triangle PDC to the area of triangle ABC is: \[ \frac{Area(PDC)}{Area(ABC)} = \frac{1}{6} \]
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