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Bony John

· started a discussion

· 1 Months ago

What if the two pints are on different sides

Question:

 P and Q on the same side of a building are two points observed  from  the top of that  building 

\( 20\sqrt[]{3}\)  m high. If the angles of the points are complementary and PQ = 40 m, then the distance of P from the building is – 

Options:
A)

     10 m 

B)

     20 m 

C)

     15 m

D)

     25 m 

Solution:

  

Here, AB is the building of height  203   m

In ∆ABP,

tan(90°-θ)=ABPB   

cotθ=203PB   .....(i)

In ABQ,

tanθ=ABQB=203QP+PB   

tanθ=20340+PB   ......(ii)

From equation (i) and (ii)

cotθ×tanθ=203PB×20340+PB   

PB(40 + PB) = 1200

PB2 + 40PB – 1200 = 0

PB2 + 60PB – 20PB – 1200 = 0

PB(PB + 60) – 20(PB + 60) = 0

(PB – 20) (PB + 60) = 0

So, PB = 20 m

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