st. lines JEE quesn

reading this quesn mite make u feel this is a 9th class quesn(it atleast made me feel so:P) but still cudnt do it:P
now i realise why my maths is weak........kaash 9th mein dhang se padh leta:P

In a triangle OAB , E is the mid-pt. of OB and D is a pt. on AB uch that AD:DB = 2:1 . If OD and AE intersect at P , determine the ratio OP:PD.

3 Answers

1
redion ·

when u go to XII you'll learn a very easy method for this in vectors, OP:PD is equal to 3:2

6
AKHIL ·

lol
:D

i am a dropper..........

and i know how to do it in vectors

but i want to know how it can be solved in coordinate...

11
jeetopper jee ·

simply consider the base am along the x axis with the coordinate a at the origin .
Now assume coordinates as given below

A(0,0)
B(α,0)
O(β,ξ)

now coordinate E is(α+β/2),
D(2α/3,0)

Equation AE=y=ξ/α+βx

OD:-y=ξ/3β-2α/3(x-2α/3)

Solving the two equations THE Y coordinate of the point is 2ξ/5

NOW if the ratio is k:1
THEn
ξ/k+1=2ξ/5
1/k+1=2/5
solving k=3/2

Thus ratio is 3:2

THIS CAN BE SOLVED BY GEOMETRY ALSO.

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