What is the cosine of the angle between two straight lines having direction ratios proportional to and ?
Answer and explanation
Correct answer: B.
- Step 1: Direction ratios are and .
- Step 2: Formula: .
- Step 3: Numerator: .
- Step 4: Since numerator is 0, (the lines are perpendicular).
Answer
.
Why not the others: Non-zero values result from arithmetic errors in the numerator sum; here exactly.
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