Mathematics_Today_-_October_2016

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  1. If the circles x^2 + y^2 – 4rx – 2ry + 4r^2 = 0 and
    x^2 + y^2 = 25 touch each other, then r satisfies
    (a) 4r^2 + 10r ± 25 = 0
    (b) 5r^2 + 10r ± 16 = 0
    (c) 4r^2 ± 10r + 25 = 0
    (d) 4r^2 ± 10r – 25 = 0

  2. If the points (0, 0), (1, 0), (0, –1) and (λ, 3λ) are
    concyclic, then λ is
    (a) 5 (b) 1/5 (c) –5 (d) –1/5

  3. The shortest distance of the point (9, –12) from the
    circle x^2 + y^2 = 16, is
    (a) 7 units (b) 11 units
    (c) 15 units (d) 4 units

  4. One extremity of a diameter of the circle
    x^2 + y^2 – 8x – 4y + 15 = 0 is (2, 1), the other extremity
    is
    (a) (0, 0) (b) (6, 3)
    (c) (4, 2) (d) (–3, –6)

  5. The triangle PQR is inscribed in the circle
    x^2 + y^2 = 25. If Q and R have coordinates (3, 4) and
    (–4, 3) respectively, then ∠QPR is equal to
    (a) π/2 (b) π/3 (c) π/4 (d) π/6

  6. The equation of a circle which passes through the
    point (h, k) and touches the y-axis at origin, is
    (a) h^2 (x^2 + y^2 ) = (h^2 + k^2 )x
    (b) h^2 (x^2 + y^2 ) = (h^2 + k^2 )y
    (c) k^2 (x^2 + y^2 ) = (h^2 + k^2 )x
    (d) k^2 (x^2 + y^2 ) = (h^2 + k^2 )y

  7. If ax^2 + (2a – 3)y^2 – 6x + ay – 3 = 0 represents a
    circle, then its radius is
    (a) 1 (b) 6 (c) 1/2 (d) 3/2

  8. Locus of a point which divides chord at a distance
    1 unit from the centre of the circle x^2 + y^2 = 1 in the
    ratio 2 : 1 is
    (a) x^2 + y^2 = 2 (b) x^2 + y^2 = 4
    (c) x^2 + y^2 = 8 (d) x^2 + y^2 = 16
    CATEGORY-II
    Every correct answer will yield 2 marks. For incorrect response,
    25% of full mark (1/2) would be deducted. If candidate marks
    more than one answer, negative marking will be done.

  9. If intercept on the line y = x by the circle
    x^2 + y^2 – 2x = 0 is AB, then equation of the circle
    with AB as diameter is
    (a) x^2 + y^2 + x + y = 0
    (b) x^2 + y^2 – x + y = 0
    (c) x^2 + y^2 – x – y = 0
    (d) x^2 + y^2 + x – y = 0
    32. The equation of the circle described on the chord
    3 x + y + 5 = 0 of the circle x^2 + y^2 = 16 as diameter
    is
    (a) x^2 + y^2 + 3x + y + 11 = 0
    (b) x^2 + y^2 – 3x – y – 11 = 0
    (c) x^2 + y^2 + 3x + y – 11 = 0
    (d) x^2 + y^2 + 3x – y – 11 = 0
    33. In a triangle ABC, if a
    cos^22 C ccos Ab,
    22


3
2

+= then
the sides a, b, c
(a) satisfy a + b = c (b) are in A.P.
(c) are in G.P. (d) are in H.P.


  1. The number of integral values of k for which the
    equation 3cosx + 4sinx = 2k + 1 has a solution, is
    (a) 3 (b) 6 (c) 4 (d) 5

  2. The number of ways in which the letters of the word
    ‘COMBINE’ can be arranged so that the word begin
    and end with a vowel, is
    (a) 30 (b) 504 (c) 360 (d) 720
    CATEGORY-III
    In this section more than 1 answer can be correct. Candidates
    will have to mark all the correct answers, for which 2 marks
    will be awarded. If candidate marks one correct and one
    incorrect answer then no marks will be awarded. But if,
    candidate makes only correct, without making any incorrect,
    formula below will be used to allot marks.
    2×(no. of correct response/total no. of correct options)

  3. If nC 4 , nC 5 and nC 6 are in A.P., then n is
    (a) 8 (b) 9 (c) 14 (d) 7

  4. If 0 ≤ x ≤ 2 π and |cosx| ≤ sinx, then
    (a) the set of values of x is ππ
    42


⎡ ,
⎣⎢


⎦⎥
(b) the number of solutions that are integral
multiples of π/4 is three
(c) the sum of the largest and the smallest solution
is 3π/4

(d) x∈⎡
⎣⎢


⎦⎥

∪⎡
⎣⎢


⎦⎥

ππ π π
42 2

3
4

,,


  1. In a ΔABC, tanA and tanB are the roots of the
    equation ab(x^2 + 1) = c^2 x, where a, b and c are the
    sides of the triangle. Then


(a) tan(AB)

ab
ab

− = −

22
2
(b) cotC = 0
(c) sin^2 A + sin^2 B = 1
(d) none of these
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