Hey there! Sign in to join this conversationNew here? Join for free

A Grade GCSE Maths Question Help Watch

Announcements
    • Thread Starter
    Offline

    2
    ReputationRep:
    Carla has made a cube out of cardboard. Each side of the cube is 12.5cm long. Carla suspends the cube from the ceiling by one corner. How far below the top corner is the bottom corner. The answer is 21.7cm. I realise I need to do Pythagoras theorem but I keep getting the wrong answer... Help please
    Offline

    1
    ReputationRep:
    When you have a cube or cuboid and want to find a diagonal length like this, it is very simple. You only need to do each length of the square, squared and added together.
    So instead of:
    a² + b² = c²
    It looks more like:
    a² +b² + c² = d² (though I don't think this is the correct notation, you should get the idea)
    So you need to do 12.5² x 3, (since each side is the same) and then square root it.
    12.5² = 156.25
    156.25 x 3 = 468.75
    If you square root this it comes out as 21.65 which rounds to 21.7
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by sometwat)
    When you have a cube or cuboid and want to find a diagonal length like this, it is very simple. You only need to do each length of the square, squared and added together.
    So instead of:
    a² + b² = c²
    It looks more like:
    a² +b² + c² = d² (though I don't think this is the correct notation, you should get the idea)
    So you need to do 12.5² x 3, (since each side is the same) and then square root it.
    12.5² = 156.25
    156.25 x 3 = 468.75
    If you square root this it comes out as 21.65 which rounds to 21.7
    Thank you so much x
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Break up or unrequited love?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.