Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    14
    ReputationRep:
    Hey guys

    Just a quick question on trigonometry.

    So I know you use cosine rule when you have :
    1. A triangle with 3 sides
    2. A triangle with 2 sides and and angle between the two sides

    Sine rule when you have :
    1. A triangle with 1 side and 2 angles

    I'm a little confused on what you do when you have a triangle with 2 sides and an angle which is not between them ( so opposite one of the sides). I remember for GCSE when I used BBC bitesize it states you use sine rule, however a cgp revision guide I have just says that the rules don't work when you have 2 sides and an able not between them.

    Please could someone kindly clarify what you do if you have a triangle and 2 sides but the angle is not between the 2 sides.

    Thanks in advance
    Offline

    14
    ReputationRep:
    You'd use the sine rule as the angle will be "opposite" one of the sides.

    Unless you mean you're trying to find the angle in which case I have no idea sorry
    Offline

    3
    ReputationRep:
    (Original post by Aty100)
    Hey guys

    Just a quick question on trigonometry.

    So I know you use cosine rule when you have :
    1. A triangle with 3 sides
    2. A triangle with 2 sides and and angle between the two sides

    Sine rule when you have :
    1. A triangle with 1 side and 2 angles

    I'm a little confused on what you do when you have a triangle with 2 sides and an angle which is not between them ( so opposite one of the sides). I remember for GCSE when I used BBC bitesize it states you use sine rule, however a cgp revision guide I have just says that the rules don't work when you have 2 sides and an able not between them.

    Please could someone kindly clarify what you do if you have a triangle and 2 sides but the angle is not between the 2 sides.

    Thanks in advance
    https://a44694f152ee562e38a9454969d2...%20Edexcel.pdf
    look at question 4 if you mean 2 sides and not the included angle( where included angle is the angle between 2 sides)
    then yes you use sine rule
    • Thread Starter
    Offline

    14
    ReputationRep:
    (Original post by thefatone)
    https://a44694f152ee562e38a9454969d2...%20Edexcel.pdf
    look at question 4 if you mean 2 sides and not the included angle( where included angle is the angle between 2 sides)
    then yes you use sine rule
    Thank youu
 
 
 
  • 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
    Have you ever participated in a Secret Santa?
    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.