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NCERT Class XII Mathematics Chapter - - Solutions

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Question : 70 of 78
Marks: +1, -0
Find the coordinates of the point where the line through (5, 1, 6) and (3, 4, 1) crosses the ZX plane.
Solution:  
The equation of line through (5, 1, 6) and (3, 4, 1) is
x−53−5=y−14−1=z−61−6\frac{x-5}{3-5}=\frac{y-1}{4-1}=\frac{z-6}{1-6}
x−5−2=y−13=z−6−5\frac{x-5}{-2}=\frac{y-1}{3}=\frac{z-6}{-5}...(1)
Any point on (1) is (5 – 2k, 1 + 3k, 6 – 5k) ...(2)
This lies on ZX plane
∴ y = 0
⇒1+3k=0⇒k=−13\Rightarrow 1+3k=0\Rightarrow k=-\frac{1}{3}
Putting the value of k=−13k=-\frac{1}{3} in (2), we get, (5+23,1−1,6+53)\left(5+\frac{2}{3},1-1,6+\frac{5}{3}\right) i.e., (173,0,233),\left(\frac{17}{3},0,\frac{23}{3}\right), is the required point.
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