JEE Advanced 2014 Mathematics question

MathematicsApplication of DerivativesJEE Advanced 2014

List I P. Let , x ∈ [−1, 1], . Then equals Q. Let (n > 2) be the vertices of a regular polygon of n sides with its centre at the origin. Let be the position vector of the point , k = 1, 2, …, n. If , then the minimum value of n is R. If the normal from the point P(h, 1) on the ellipse is perpendicular to the line x + y = 8, then the value of h is S. Number of positive solutions satisfying the equation is List II 1. 1 2. 2 3. 8 4. 9

Answer: (A)

Solution

P: with x = cos θ, y = cos3θ; and differentiating again gives . Hence and the expression equals 9 → 4. Q: each term has (all in the same direction) and $Missing argument for \vec\vec

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Question ID VK-026362