From the first relation, . Putting this value of l in second relation

Note that it, being quadratic in m, n, gives two sets of values of m, n, and hence gives the d.r.s. of two lines.
Now, factorizing it, we get

Taking we get .
Also putting in , we get

Thus, we get, or
⇒ d.r.'s of one line are .
Hence, the dc's. of one line are

Taking , we get

Putting this value in , we obtain

Thus
⇒ the d.r's of the second line are ; and hence d.c.s. of second line are

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