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If the lines x=ay+bx = ay+b, z=cy+dz = cy+d and x=py+qx = py+q, z=ry+sz = ry+s are perpendicular, then ap+crap + cr is equal to

Solution

✅ Correct Option: 3

Writing each line in symmetric form with yy as parameter, the direction ratios are (a,1,c)(a,1,c) and (p,1,r)(p,1,r). Perpendicularity gives ap+1+cr=0ap + 1 + cr = 0, so ap+cr=−1ap + cr = -1.

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