Assertion :Three concurrent lines with direction cosines l1,m1,n1;l2,m2,n2;l3,m3,n3 are coplanar if ∣∣
∣∣l1m1n1l2m2n2l3m3n3∣∣
∣∣=0
Reason: Lines x−x1l1=y−y1m1=z−z1n1,x−x2l2=y−y2m2=z−z2n2 are coplanar if ∣∣
∣∣x−x1y−y1z−z1l1m1n1l2m2n2∣∣
∣∣=0
A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
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B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
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C
Assertion is correct but Reason is incorrect
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D
Assertion is incorrect but Reason is correct
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Solution
The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion Given Three concurrent lines with direction cosines l1,m1,n1;l2,m2,n2;l3,m3,n3 are coplanar if ∣∣
∣∣l1m1n1l2m2n2l3m3n3∣∣
∣∣=0
Thus assertion is correct.
Lines x−x1l1=y−y1m1=z−z1n1,x−x2l2=y−y2m2=z−z2n2 are coplanar if ∣∣
∣∣x−x1y−y1z−z1l1m1n1l2m2n2∣∣
∣∣=0.
Also reason is correct but reason is not correct explanation for assertion
Thus Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion