CBSE BOARD X, asked by sanjkum1974, 9 months ago

Please solve it
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Answered by Anonymous
4

\huge{\boxed{\mathcal\pink{\fcolorbox{red}{yellow}{Answer}}}}

To prove:

The height of the point of interaction pf the lime joining the top of each tree to the foot of the opposite tree is given as {\bold{\boxed{\red{\frac{ab}{a + b} metre}}}}

solution:

height of the two trees AB and CD be b and a respectively.

Distance between the trees BC = p

Let EF = h be the height of point of intersection of the lines joining the top of each tree to the foot of the opposite trees.

Let CF = x then BF = (p – x)

In Δ’s ABC and EFC, ∠ABC = ∠EFC = 90° ∠C = ∠C (common angle)

 \frac{b}{p}  =  \frac{h}{x}

{\bold{\boxed{\pink{\tt{bx=ph}}}}}

x =  \frac{ph}{b}

ΔABC ~ ΔEFC (By AA similarity theorem) Similarly, ΔDCB ~ ΔEFB (By AA similarity theorem)

 \frac{a}{p}  =  \frac{h}{p - x }  \\ ap - ax = ph

ap - a \times  \frac{ph}{b}  = ph

p(a -  \frac{ah}{b}  )= ph

  \frac{ab-ah}{b}  = h

ab -ah=bh

ab =ah+bh

ab= h(a+b)

{\bold{\boxed{\red{h=\frac{ab}{a+b}}}}}

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