Show that the straight lines whose direction cosines are given by the equations `a l+b m+c n=0a n dul^2+z m^2=v n^2+w n^2=0` are parallel or perpendicular as `(a^2)/u+(b^2)/v+(c^2)/w=0ora^2(v+w)+b^2(w+u)+c^2(u+v)=0.`

Explanation

Here, `l=−(bm+cn)/a`​ and `ul^2+m^2v+wn^2=0`


Eliminating l, we get


`u(bm+cn)^2/a^2​+vm^2+wn^2=0`


⇒`(b^2u+a^2v)(m/n​)^2+(2bcu)(m/n​)+(c^2u+a^2w)=0`


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