### Discussion :: Force Vectors - General Questions (Q.No.1)

D.Vengadesan said: (Dec 15, 2010) | |

Sir I want explanation for this answer. |

Jay Aswani said: (Jan 4, 2012) | |

Sir please provide complete solution so that we can take advantage of that. |

Mr. Right said: (Sep 9, 2013) | |

The answer is actually 7.68. The diagram is not a right triangle, as it is in 3 dimensions and not on an x,y axis. Correct approach: A=0i+1j+4z. B=?i+0j+2z. Distance between 2 points in 3d: sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2). (x-0)^2 + (0-1)^2 + (2-4)^2. x^2 + 1 + 4 = 8^2. x^2=59. x= sqrt59 = 7.68115. Now if you check that you will see that it is correct, as opposed to the answer that you all tried to simplify and didn't bother to check your work. |

Second Right said: (Jul 26, 2014) | |

I agree with Mr. Right, there are two perpendicular right triangles that you must solve. This is an engineering mechanics question, not a grade 10 trigonometry question. The answer is x=sqrt(59). |

Riyaz Ibrahim said: (Oct 5, 2015) | |

I am not satisfied, try to solve in simple format. |

Woxiiii said: (Nov 22, 2015) | |

It's 3D Pythagoras so all you have to do is substitute into the formula a^2+b^2+c^2=d^2. |

Abdul Khaleqaue said: (Dec 22, 2015) | |

Suppose B point at black wall and A point at white wall. Draw a line perpendicular to white wall. Now apply Pythagoras formula. You will find square root of (8^2-(4-2)^2) = 7.7459. It will give you hypotenuse of new triangle. Again apply same formula square root of (7.7459^2-1^2) = 7.68. |

Karthi said: (Dec 28, 2015) | |

Sir I cannot understand so please explain. |

Nicky said: (Feb 17, 2016) | |

Please explain it into details. |

Susheel said: (Feb 29, 2016) | |

More explain. |

Alex said: (May 2, 2017) | |

Please, can anyone make it clear? |

Prahlad said: (Oct 3, 2017) | |

2^2-8^2-1^2=59 , Then √59=7.68. |

Kunal said: (Jan 19, 2019) | |

8^2=1^2+2^2+x^2. x^2=59, x = 7.68, |

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