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

    16
    ReputationRep:
    Hi all,

    Can anyone shed some light on how to go about solving this question?

    (Question 7, for clarity).

    Thank you!
    Attached Images
  1. File Type: pdf Attachment-1.pdf (278.7 KB, 81 views)
    Offline

    22
    ReputationRep:
    (Original post by londoncricket)
    Hi all,

    Can anyone shed some light on how to go about solving this question?

    (Question 7, for clarity).

    Thank you!
    It's right angled, you should write down: a^2 + b^2 = c^2 immediately.

    Furthermore, you can see that \cos \theta = \frac{a}{c} and \tan \theta = \frac{b}{a}.

    Can you take it from here?
    Offline

    2
    What level maths is this? (GCSE, C1, C2?
    Offline

    22
    ReputationRep:
    (Original post by Oblivion99)
    What level maths is this? (GCSE, C1, C2?
    Anybody doing GCSE should be able to do it.
    Offline

    12
    ReputationRep:
    (Original post by Zacken)
    Anybody doing GCSE should be able to do it.
    I don't get how tan of theta is a/b i thought it would be b/a because b is the opposite
    Offline

    22
    ReputationRep:
    (Original post by okey)
    I don't get how tan of theta is a/b i thought it would be b/a because b is the opposite
    Yep, that's correct. Thanks for pointing it out, must have gotten confused because of all the neck craning I was doing. :lol:
    • Thread Starter
    Offline

    16
    ReputationRep:
    (Original post by Zacken)
    It's right angled, you should write down: a^2 + b^2 = c^2 immediately.

    Furthermore, you can see that \cos \theta = \frac{a}{c} and \tan \theta = \frac{b}{a}.

    Can you take it from here?
    Got it. Thanks!

    (Original post by Oblivion99)
    What level maths is this? (GCSE, C1, C2?
    Additional Maths at GCSE level.
    Offline

    22
    ReputationRep:
    (Original post by Oblivion99)
    Solved it. Its actually quite easy, yes. As someone stated above, just take note of the trigonometric identities (i.e cos 0 = a/b tan = b/c) and then you should be able to take it from here
    These are both wrong.
    Offline

    2
    (Original post by Zacken)
    These are both wrong.
    Can you provide me a step to step method onto solving this Q. Yes, ive actually flopped it
    Offline

    22
    ReputationRep:
    (Original post by Oblivion99)
    Can you provide me a step to step method onto solving this Q. Yes, ive actually flopped it
    Tell you what, I'll let the OP do it - it'll be good practice for him/her.


    (Original post by londoncricket)
    ...
    If he doesn't reply, then tag me in a bit and I will. :yep:
    Offline

    19
    ReputationRep:
    (Original post by Zacken)
    Anybody doing GCSE should be able to do it.
    hmmm ...
    Attached Images
     
    Offline

    2
    (Original post by Zacken)
    Tell you what, I'll let the OP do it - it'll be good practice for him/her.




    If he doesn't reply, then tag me in a bit and I will. :yep:
    Its been an hour so
    Offline

    22
    ReputationRep:
    (Original post by Oblivion99)
    Its been an hour so
    If you look at the triangle and select the angle theta, then the adjacent over hypotenuse (i.e: cos) is: \cos \theta = \frac{a}{c}

    The tangent is: \displaystyle \tan \theta \frac{b}{a} (opposite over adjacent)

    We also know it's a right angled triangle, so: a^2 + b^2 = c^2.

    Squaring and taking the reciprocal of cosine: \frac{1}{\cos^2 \theta} = \frac{c^a}{a^2}

    And also: 1 + \tan^2 \theta = 1 + \frac{b^2}{a^2} = \frac{a^2 + b^2}{a^2}

    But since a^2 +b^2 = c^2 then, 1 + \tan^2 \theta = \frac{c^2}{a^2} = \frac{1}{\cos^2 \theta} as required.
 
 
 
  • 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
    Would you like to hibernate through the winter months?
    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.