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Question -

Find the points on z-axis which are at a distanceтИЪ21 from the point (1, 2, 3).



Answer -

Given:

The point (1, 2, 3)

Distance = тИЪ21┬а

We know x = 0 and y = 0 on z-axis

Let R(0, 0, z) any point on z-axis

According to question:

RA = тИЪ21┬а

RA2┬а= 21

By using the formula,

The distance┬аbetween any two points (a, b, c) and (m, n, o)is given by,

We know, RA2┬а= 21

5 + (z тАУ 3)2┬а= 21

z2+ 9 тАУ 6z + 5 = 21

z2┬атАУ 6z = 21 тАУ 14

z2тАУ 6z тАУ 7 = 0

z2тАУ 7z + z тАУ 7 = 0

z(zтАУ 7) + 1(z тАУ 7) = 0

(zтАУ 7) (z + 1) = 0

(zтАУ 7) = 0 or (z + 1) = 0

z= 7 or z = -1

тИ┤The┬аpoints(0, 0, 7) and (0, 0, -1)┬аon z-axis is equidistant from┬а(1, 2, 3).

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