Question

The condition for the lines $lx+ my + n = 0$ and $l_1x + m_1y + n_1 = 0$ to be conjugate with respect to the circle $x^2 + y^2 = r^2$ is

• A. $r^2 (ll_1 + mm_1) = nn_1$
• B. $r^2 (ll_1 - mm_1) = nn_1$
• C. $r^2 (ll_1 - mm_1) =+nn_1=0$
• D. $r^2 (lm_1 +mm_1) = nn_1$

Answer 1

Answer: (A)

$r^2 (ll_1 + mm_1) = nn_1$

Answer 2

Answer (a) $r^2 (ll_1 + mm_1) = nn_1$