CBSE Class 12 Math 2020 Outside Delhi Set 3 Solved Paper

Question : 11

Total: 11

Find the image of the point (−1,3,4) in the plane x−2y=0.

Solution: 👈: Video Solution

We know that the image (x,y,z) of point(x1,y1z1)
In a plane ax+by+cz+d=0 is
‌

x−x1

=‌

y−y1

=‌

z−z1

=‌

−2(ax1+by1+cz1+d)

a2+b2+c2

Thus, the image of point (−1,3,4) in a plane x−2y=0 is
‌

x+1

=‌

y−3

−2

=‌

z−4

=‌

−2[1(−1)+(−2)3+0(4)]

1+0+4

‌

x+1

=‌

y−3

−2

=‌

z−4

=‌

−2(−7)

x=‌

−1=‌

;y=‌

−28

+3=‌

−13

z=4
∴ Image of (−1,3,4) is (‌

,‌

,4)

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