Results 1 to 2 of 2

Thread: Help with year 11 Trig 3 unit

  1. #1
    Cadet
    Join Date
    Aug 2016
    HSC
    N/A
    Gender
    Undisclosed
    Posts
    94
    Rep Power
    1

    Help with year 11 Trig 3 unit

    Can anyone please help me answer these two questions. I only managed to get half the working out right.

    I attached the questions below

    Thankyou

  2. #2
    Loquacious One
    Join Date
    Feb 2009
    HSC
    N/A
    Gender
    Male
    Posts
    3,584
    Rep Power
    9

    Re: Help with year 11 Trig 3 unit

    I recall doing the 2nd question late last year.

    The basic idea is very simple. Say if you draw a right-angled triangle ABC, right-angled at B, with hypotenuse of length 7 say, then the 2 shorter sides are AB = 7 cos A and BC = 7 sin A.

    Now for this question, form the 3 right angled triangles with hypotenuses AP, PQ and QR (each of length x, say) resp., with their shorter sides parallel to, and vertical to side AB respectively. Also drop the perpendicular to line AB from R, meeting AB at Z say.

    Then tan(angle BAR) = RZ/AZ

    Now RZ is the sum of the vertcal sides of the 3-right angled triangles, and
    AZ is the sum of the 3 horizontal sides. Therefore:

    RZ = x sin @ + x sin 2@ + x sin 3@ = x (sin@ + sin 2@ + sin 3@)

    AZ = xcos @ + x cos 2@ + x cos 3@ = x (cos @ + cos 2@ + cos 3@)

    Hence the result.
    Last edited by Drongoski; 18 Apr 2017 at 11:54 PM.
    1-on-1 Maths Tutoring(IB & HSC): Epping, Beecroft, Eastwood, Carlingford & Beyond
    IB: Maths Studies, Maths SL & Maths HL; HSC: 2U, 3U & 4U
    Highly Qualified & Highly Experienced. Estimated ATAR > 9.995
    There are IB Maths Tutors and there are IB Maths Tutors.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •