PYQ Vault

Day 39: NDA Maths

5 questions (7 parts). Try each one first, then open its answer.

  1. Question 1

    Vectors. This type asked 3 times: NDA 1 2017, NDA 1 2019, NDA 2 2022. This one: NDA 2 2022

    69
    What are the values of x for which the angle between the vectors 2x2i^+3xj^+k^2x^2\hat{i}+3x\hat{j}+\hat{k} and i^−2j^+x2k^\hat{i}-2\hat{j}+x^2\hat{k} is obtuse?

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  2. Question 2 (case study, 3 parts)

    3D Geometry. This type asked 3 times: NDA 2 2017, NDA 1 2018, NDA 1 2022. This one: NDA 1 2022

    Consider the following for the next three (03) items that follow: The plane 6x+ky+3z−12=06x+ky+3z-12=0 where keq0k eq0 meets the coordinate axes at AA, BB and CC respectively. The equation of the sphere passing through the origin and AA, BB, CC is x2+y2+z2−2x−3y−4z=0x^2+y^2+z^2-2x-3y-4z=0.
    91
    What is the value of kk?

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    92
    If pp is the perpendicular distance from the centre of the sphere to the plane, then which one of the following is correct?

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    93
    What is the equation of the line through the origin and the centre of the sphere?

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  3. Question 3

    Application of Derivatives. This type asked 3 times: NDA 1 2020, NDA 1 2021, NDA 1 2022. This one: NDA 1 2022

    66
    What is the maximum value of the function f(x)=1tan⁡x+cot⁡xf(x)=\frac{1}{\tan x+\cot x}, where 0<x<π20<x<\frac{\pi}{2}?

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  4. Question 4

    Functions. This type asked 3 times: NDA 2 2018, NDA 1 2019, NDA 1 2022. This one: NDA 1 2022

    59
    What is the domain of the function f(x)=1−(x−1)2f(x)=\sqrt{1-(x-1)^2}?

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  5. Question 5

    Matrices & Determinants. This type asked 3 times: NDA 2 2017, NDA 2 2018, NDA 1 2022. This one: NDA 1 2022

    2
    If (a−b)(b−c)(c−a)=2(a-b)(b-c)(c-a) = 2 and abc=6abc = 6, then what is the value of ∣abca2b2c2a3b3c3∣\begin{vmatrix}a & b & c\\a^2 & b^2 & c^2\\a^3 & b^3 & c^3\end{vmatrix}?

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