Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET202121 Sep 2021Morning ShiftMathematicsVector AlgebraActual

If a =3 i -5 j , b =6 i -3 j are two vectors and c is vector such that c = a b , then a: b: c is

Options

  1. A34 : 45 : 39
  2. B34 : 45 : 39
  3. C34: 39: 45
  4. D39: 35: 34

Correct answer

B. 34 : 45 : 39

Step-by-step solution

aligned & c = a b = | array ccc i & j & k 3 & -5 & 0 6 & 3 & 0 array |= i (0)- j (0)+ k (9+30)=39 k & | a |= (3)^2+(-5)^2 = 34 and | b |= (6)^2+(3)^2 = 45 & | c |= 39^2 =39 & a : b : c = 34 : 45 : 39 aligned

Practice Vector Algebra on Quantrex Academy →

More from Vector Algebra

P is the circumcentre of A B C . If the position vectors of A, B, C and P are a , b , c , a + b + c 4 respectively, then the position vector of the orthocentre of this triangle is 2025If the position vectors of A, B, C, D are i +2 j +2 k , 2 i - j , i + j +3 k and 4 j +5 k respectively, then the quadrilateral ABCD is a 2025The set of all real values of c so that the angle between the vectors a = cx i -6 j +3 k and b =x i +2 j +2 cx k is an obtuse angle for all real x is 2025Let a =2 i + j +3 k , b =3 i +3 j + k and c = i -2 j +3 k be three vectors. If r is a vector such that r a = r b and r c =18 , then the magnitude of the orthogonal projection of 4 2025If u , v , w are non coplanar vectors and p, q are real numbers, then the equality [ array lll 3 u & p v & p w array ]- [ array lll p v & w & q u array ]- [ array lll 2 w & q v & q 2025Let i -2 j + k , i + j -2 k , 2 i - j - k and i + j + k be the position vectors of four points A , B , C and D respectively. If a point P divides AB in the ratio 2: 1 internally an 2025If a = i + j , b =2 j - k are two vectors such that r a = b a , r b = a b , then the unit vector in the direction of r is 2025If a , b , c are three unit vectors such that a ( b c )= 3 2 b + c 2 and , are the angles between a , c and a , b respectively, then + = 2025 Full Vector Algebra list All MHT CET PYQs