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प्रश्न
In ∆ABC, B - D - C and BD = 7, BC = 20 then find following ratio.

`"A(∆ ABD)"/"A(∆ ADC)"`
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उत्तर
Construction: Draw a perpendicular from vertex A to line BC.

BC = BD + DC ...[B - D - C]
DC = BC − BD
DC = 20 − 7
DC = 13
Ratio of areas of two triangles is equal to the ratio of the products of their bases and corresponding heights.
∴ `"A(∆ ABD)"/"A(∆ ADC)" = (1/2 xx "AX" xx "BD")/(1/2 xx "AX" xx "DC")`
∴ `"A(∆ ABD)"/"A(∆ ADC)" = "BD"/"DC"`
∴ `"A(∆ ABD)"/"A(∆ ADC)" = 7/13`
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In the figure, PQ ⊥ BC, AD ⊥ BC. To find the ratio of A(ΔPQB) and A(ΔPBC), complete the following activity.

Given: PQ ⊥ BC, AD ⊥ BC
Now, A(ΔPQB) = `1/2 xx square xx square`
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Therefore,
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= `square/square`
