if two mutually perpendicular lines with their direction cosines are given and we have to find out the direction cosine of a line perpendicular to both given lines.then how we will find out.

dear Mohummed Imran,

Let us consider the DR's of two perpendicular lines be (l1.m1,n1) and (l2,m2,n2)

and the other one be (l3,m3,n3)

then,

l1 * l3+ m1 * m3 + n1*n3=0

and l2*l3 + m2*m3 + n2*n3 = 0

using the above two equations we can establish a relationship between l3,m3,n3 and other thus find out the DRs

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