Question
If AD is median of ΔABC and P is a point on AC such that ar(ΔADP) : ar(ΔABD) = 2 : 3, then ar(ΔPDC) : ar(ΔABC) is
If AD is median of ΔABC and P is a point on AC such that ar(ΔADP) : ar(ΔABD) = 2 : 3, then ar(ΔPDC) : ar(ΔABC) is
Answer: Option D
:
D
Given : AD is median of Δ ABC
∴BD=DC
ar(ΔADP) : ar(ΔABD) = 2 : 3
To find:ar(ΔPDC) : ar(ΔABC)
Construction: Draw XY ∥ BC
Median divides the triangle into two equal areas and
Triangle ABD and ADChave equal baseBD and CD and are within the same parallels XY and BC.
∴ area Δ ABD = area Δ ADC...(i)
area Δ ABD: area Δ ABC = 1 : 2 ...(ii)
area Δ ADP : area Δ ABD = 2 : 3 …(iii)
area Δ ADC = area Δ ADP +area Δ PDC
area Δ ABD= area Δ ADP +area Δ PDC
area Δ PDC
=area Δ ABD -area Δ ADP
=area Δ ABD - 23area Δ ABD
=13area Δ ABD
∴area Δ PDC : area Δ ABD = 1 : 3...(iv)
areaΔPDCareaΔABC=13×12 ….. (from equations (i) and (iv)
area Δ PDC : area Δ ABC = 1 : 6
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:
D
Given : AD is median of Δ ABC
∴BD=DC
ar(ΔADP) : ar(ΔABD) = 2 : 3
To find:ar(ΔPDC) : ar(ΔABC)
Construction: Draw XY ∥ BC
Median divides the triangle into two equal areas and
Triangle ABD and ADChave equal baseBD and CD and are within the same parallels XY and BC.
∴ area Δ ABD = area Δ ADC...(i)
area Δ ABD: area Δ ABC = 1 : 2 ...(ii)
area Δ ADP : area Δ ABD = 2 : 3 …(iii)
area Δ ADC = area Δ ADP +area Δ PDC
area Δ ABD= area Δ ADP +area Δ PDC
area Δ PDC
=area Δ ABD -area Δ ADP
=area Δ ABD - 23area Δ ABD
=13area Δ ABD
∴area Δ PDC : area Δ ABD = 1 : 3...(iv)
areaΔPDCareaΔABC=13×12 ….. (from equations (i) and (iv)
area Δ PDC : area Δ ABC = 1 : 6
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