Question

Question Info and Solutions Let P= (1, 2, x), Q = (a x y), R= (x,y,z) then PxQ is
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Answer 1

Answer:

where 1,2

Step-by-step explanation:

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Answer 2

Answer:

Consider the reflection of point P in the x−axis P

′

P

′

≡(1,−1)

The x−axis is the ⊥ar bisector of PP

′

RP=RP

′

Adding RQ

RP+RQ=RP

′

+RQ

The sum (RP

′

+RQ) is min. when R lies on the line joining P

′

and Q.

Now the eqn of the line joining P

′

(1,−1) & Q(3,2)

(y+1)=

3−1

2+1

(x−1)

y=−1+

2

3x

−

2

3

y=

2

3x

−

2

5

The point R lying on x−axis has coordinate zero. So let it have coordinate (a,0) Since R lies on P

′

Q;it should satisfy the eqn of P

′

Q.

0=

2

3a

−

2

5

a=

2

5

R(0,

2

5

)