Home
Class 12
MATHS
Suppose a and b are two non-zero vectors...

Suppose a and b are two non-zero vectors and angle between a and b is `theta, " where "0 lt theta lt pi//2`. If `abs(a times b)=abs(a*b)," then "pi//theta=`_______

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( \frac{\pi}{\theta} \) given that the magnitudes of the cross product and the dot product of two non-zero vectors \( \mathbf{a} \) and \( \mathbf{b} \) are equal, and the angle \( \theta \) between them is in the range \( 0 < \theta < \frac{\pi}{2} \). ### Step-by-step Solution: 1. **Write the expressions for the cross product and dot product:** - The magnitude of the cross product is given by: \[ |\mathbf{a} \times \mathbf{b}| = |\mathbf{a}| |\mathbf{b}| \sin \theta \] - The dot product is given by: \[ \mathbf{a} \cdot \mathbf{b} = |\mathbf{a}| |\mathbf{b}| \cos \theta \] 2. **Set the magnitudes equal:** Since the magnitudes of the cross product and the dot product are equal, we have: \[ |\mathbf{a} \times \mathbf{b}| = |\mathbf{a} \cdot \mathbf{b}| \] This gives us the equation: \[ |\mathbf{a}| |\mathbf{b}| \sin \theta = |\mathbf{a}| |\mathbf{b}| \cos \theta \] 3. **Cancel the common terms:** Since \( |\mathbf{a}| \) and \( |\mathbf{b}| \) are both non-zero, we can divide both sides by \( |\mathbf{a}| |\mathbf{b}| \): \[ \sin \theta = \cos \theta \] 4. **Solve for \( \theta \):** The equation \( \sin \theta = \cos \theta \) holds true when: \[ \theta = \frac{\pi}{4} \] 5. **Calculate \( \frac{\pi}{\theta} \):** Now, substituting \( \theta = \frac{\pi}{4} \) into \( \frac{\pi}{\theta} \): \[ \frac{\pi}{\theta} = \frac{\pi}{\frac{\pi}{4}} = 4 \] ### Final Answer: Thus, the value of \( \frac{\pi}{\theta} \) is \( 4 \).
Promotional Banner

Topper's Solved these Questions

  • VECTOR ALGEBRA

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. AIEEE/JEE MAIN PAPERS|65 Videos
  • VECTOR ALGEBRA

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. B-ARCHITECTURE ENTRANCE EXAMINATION PAPERS|20 Videos
  • VECTOR ALGEBRA

    MCGROW HILL PUBLICATION|Exercise EXERCISE (Level-2 Single Correct Answer Type Questions)|32 Videos
  • TRIGONOMETRICAL IDENTITIES AND EQUATIONS

    MCGROW HILL PUBLICATION|Exercise Questions from Previous Years. B-Architecture Entrance Examination Papers|20 Videos

Similar Questions

Explore conceptually related problems

If bar(a) and bar(b) are two non-zero vectors and theta is angle between then,the cos theta is

If bar(a) and bar(b) are two non-zero vectors and theta is angle between then,the cos theta is

The angle theta between two non-zero vectors bar(a) and bar(b) is given by cos theta =….

Let a=2lambda^(2)i+4lambdaj+k" and "b=7i-2j+lambdak . The number of values of lambda for which angle between a and b is theta , where pi//2 lt theta lt pi and angle between b and k is phi " where "0 lt varphi lt pi//6 , is _______

If tan8 theta = cot 2 theta , where 0 lt 8 theta lt pi/2 , then what is the value of tan 5 theta ?

Let -> a and -> b be two unit vectors and is the angle between them. Then -> a+ -> b is a unit vector if (A) theta=pi/4 (B) theta=pi/3 (C) theta=pi/2 (D) theta=(2pi)/3

MCGROW HILL PUBLICATION-VECTOR ALGEBRA-EXERCISE (Numerical Answer Type Questions)
  1. Let ABCD be a parallelogram whose diagonals intersect at point P. Supp...

    Text Solution

    |

  2. If ABCDEF is a regular hexagon , then bar(AB) + bar(AC) + bar(AE) + ...

    Text Solution

    |

  3. Suppose a and b are two non-zero vectors and angle between a and b is ...

    Text Solution

    |

  4. Suppose a, b, c are three vectors such that abs(a)=7. If a + b + c = 0...

    Text Solution

    |

  5. Suppose a, b, c are three vectors such that a+b+c=0, abs(a)=abs(b)=1" ...

    Text Solution

    |

  6. Suppose a, b, c are three vectors such that abs(a)=abs(b)=abs(c)=1" an...

    Text Solution

    |

  7. Suppose -i+j-k bisects the angle between the vector c and 3i+4j." If "...

    Text Solution

    |

  8. Suppose a, b, c gt 0 and are respectively the pth, qth and rth terms o...

    Text Solution

    |

  9. Let a=2lambda^(2)i+4lambdaj+k" and "b=7i-2j+lambdak. The number of val...

    Text Solution

    |

  10. Suppose a, b, c are three non-coplanar vectors. Suppose Delta=|{:(a*...

    Text Solution

    |

  11. Suppose a, b, c are three non-coplanar vectors, then ((a+b+c)*((a+c)...

    Text Solution

    |

  12. Suppose A(1), A(2), …, A(5) are vertices of a regular pentagon with O ...

    Text Solution

    |

  13. Suppose a, b, c are three non-zero vectors such that b and c are non-c...

    Text Solution

    |

  14. Let alpha=3i+j" and "beta=2i-j+3k." Suppose "beta=beta(1)-beta(2)," wh...

    Text Solution

    |

  15. Let a=i-2j+k" and "b=i-j+lambdak, (where lambda in Z) be two vectors. ...

    Text Solution

    |

  16. The vectors, p=(a+1)i+aj+ak, q=ai+(a+1)j+ak" and "r=ai+aj+(a+q)k. If 3...

    Text Solution

    |

  17. Suppose OA=2i+2j+k, OB=3i+4j+12k. If OC=1/16(45i+aj+bk) is internal an...

    Text Solution

    |

  18. Let A=(2alpha, 1,alpha), B=(2, 1, 3), C=3i-j+4k." If "AB times C=5i-9j...

    Text Solution

    |