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MHT CET202014 Oct 2020Evening ShiftMathematicsThree Dimensional GeometryActual

If the angle between the lines whose direction ratios are 4,-3,5 and 3,4, k is 3 , then k=

Options

  1. A7
  2. B10
  3. C5
  4. D6

Correct answer

C. 5

Step-by-step solution

aligned 3 &= | 4(3)+(-3)(4)+5 k 4²+(-3)²+5² 3²+4²+ k ² | 1 2 &= | 5 k 5 2 25+ k ² | aligned On squaring both side we get aligned & 1 4 = 25 k ² 50 (25+ k ² ) & 100 k ²=50 (25+ k ² ) k ²=25 k = 5 aligned

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