Mathematics · JEE | THREE DIMENSIONAL GEOMETRY
हिन्दीGiven below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The line passing through the points \( (1, -1, 2) \) and \( (3, 4, -2) \) is perpendicular to the line passing through \( (0, 3, 2) \) and \( (3, 5, 6) \). Reason (R): Two lines with direction ratios \( a_1, b_1, c_1 \) and \( a_2, b_2, c_2 \) are perpendicular if and only if \( \frac{a_1}{a_2} = \frac{b_1}{b_2} = \frac{c_1}{c_2} \). In the light of the above statements, choose the correct answer from the options given below:
View Answer & Solution
Correct answer · Option C
(A) is true but (R) is false.
Explanation
Direction ratios are \( (2, 5, -4) \) and \( (3, 2, 4) \). Their dot product is \( 2(3) + 5(2) + (-4)(4) = 6 + 10 - 16 = 0 \), so they are perpendicular (A is true). Reason (R) states the condition for parallelism, not perpendicularity, so (R) is false.