EnglishUPPSC Ashram Paddhati 2021
Q41.ABCD is a parallelogram with AC and BD as its diagonals, then AC – BD is equal to
Correct answer: 2 AB
EnglishUPPSC Ashram Paddhati 2021
Q42.The angle between the vectors a×b and b×a is
Correct answer: 180°
EnglishUKPSC Lecturer (Mains) 2020
Q43.The angle between a diagonal of a cube and its coterminous edge is:
Correct answer: 1 1 cos 3 −
EnglishUKPSC Lecturer (Mains) 2020
Q44.If a,b,c are three unit vectors such that a +b +c = 0, then a.b + b.c + c.a is equal to:
Correct answer: -3/2
EnglishUKPSC Lecturer (Mains) 2020
Q45.A two dimensional vector a has its components 2p and 1 with respect to a rectangular cartesian system. This system is rotated through a certain angle about the origin in anti-clockwise direction. If, with respect to new system, a has components p + 1 and 1 then
Correct answer: p = 1 or p = 1 3 −
EnglishUKPSC Lecturer (Mains) 2020
Q46.If the vectors ˆ ˆ ˆ αi+j+k, ˆ ˆ ˆ i +βj+k and ˆ ˆ ˆ i +j+γk are coplanar, then the value of 1 1 1 1 α 1 β 1 γ + + − − − is:
Correct answer: 1
EnglishUKPSC Lecturer (Mains) 2020
Q47.If, for any vector a, it is given that () () () 2 2 2 2 ˆ ˆ ˆ a i a j a k α a, × + × + × = then the value of α is:
Correct answer: 2
EnglishUKPSC Lecturer (Mains) 2020
Q48.If a,b and c are any three vectors, then the value of a –b, b –c,c –a is:
Correct answer: None of these
EnglishUKPSC Lecturer (Mains) 2020
Q49.Let vectors α (4y)a (2 y 1)b = + + + + x x and β (y 2 2)a (2 3y 1)b = − + + − − x x, where a and b are non-zero and non-collinear. If 3α 2β =, then
Correct answer: x= 2, y = –1
EnglishUP TGT 1999 UKPSC Lecturer (Mains) 2020
Q50.If a and b are two unit vectors inclined at an angle of 600 to each other then-
Correct answer: a b 3 + =
EnglishUKPSC Lecturer (Mains) 2020
Q51.If a b c 0 + + = and a 3, b 5, c 7 =, then the angle between a and b is:
Correct answer: 1 1 cos 2 −
EnglishUKPSC Lecturer (Mains) 2020
Q52.The number of distinct real values of λ,for which the vectors – and 2 ˆ ˆ ˆ i + j – λ k are coplanar is:
Correct answer: 3
EnglishUKPSC Lecturer (Mains) 2020
Q53.If ˆ ˆ ˆ ˆ ˆ ˆ a = i + 4j + 2k, b = 3i – 2j + 7k and ˆ ˆ ˆ c = 2i – j+ 4k, then a vector d which is perpendicular to both a and b and satisfies c. d =15, is:
Correct answer: 5 ˆ ˆ ˆ (32i j 14k) 3 − −
Q54.a = 2i + j – k and b = j+ k. Vector c is such that a.c = 4 and a×c = b, then c is:
Correct answer: ˆ ˆ ˆ i j k + −
Q55.The value of 'a' for which the points A,B,C with position vectors ˆ ˆ ˆ 2i j k − +, ˆ ˆ ˆ i 3j 5k − −, ˆ ˆ ˆ ai – 3j k + and respectively are the vertices of right- angled triangle with ∠ ∠ ∠C = 2 π, are:
Correct answer: 2 and 1
Q56.a i j, = + b j k = + and c xa yb = +. If ˆ i 2j k, 3i 2j k − + + − and c are coplanar, then x y =
Correct answer: –3
Q57.The vector in the direction of the vector ˆ ˆ ˆ i 2j 2k − + − + that has magnitude 9 is:
Correct answer: () ˆ ˆ ˆ 3 i 2j 2k − +
Q58.a2 b2 – () 2 a×b =
Correct answer: () 2 a.b
Q59.Let ˆ ˆ ˆ ˆ a = i + j and b = 2i - k, then the point of intersection of the lines r×a = b×a and r×b = a×b is:
Correct answer: (3, 1, –1)
Q60.If the position vector a of a point (12, n) is such that a = 13, then the value of n is
Correct answer: ±5