Results 1 to 3 of 3

Math Help - trig

  1. #1
    Senior Member
    Joined
    Oct 2008
    Posts
    323

    trig

    1.A ladder leans up against a building at an angle of 65 with the ground. If the ladder is 5 metres long, how far up the building does it reach?

    2.A student is overheard saying: "I don't need to learn the Primary Trig Ratios. I am just going to use the Sine and Cosine Laws to solve problems." Show by example that the student is right. Explain the advantages and disadvantages to this approach.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Sep 2008
    From
    West Malaysia
    Posts
    1,261

    RE:

    Quote Originally Posted by william View Post
    1.A ladder leans up against a building at an angle of 65 with the ground. If the ladder is 5 metres long, how far up the building does it reach?
    Just apply basic trigo to this question , perhaps draw a diagram so that you can see a clearer picture .

    sin 65 = height / 5
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1

    Trigonometry

    Hello william
    Quote Originally Posted by william View Post
    2.A student is overheard saying: "I don't need to learn the Primary Trig Ratios. I am just going to use the Sine and Cosine Laws to solve problems." Show by example that the student is right. Explain the advantages and disadvantages to this approach.
    Draw a right-angled triangle ABC, with \hat{A}= 90^o.

    (a) Now write down the Sine Rule (Law), and simplify it using the fact that \sin90^o = 1. Using this simplified equation, write down expressions for \sin B and \sin C.

    (b) Write down the Cosine Rule (Law) that begins a^2 = \dots, and simplify it using the fact that \cos 90^o =0. What well-known formula does this give you?

    Can you see why the student is right in saying he doesn't need to learn the Primary Trig Ratios?

    (c) One advantage of this method is that there aren't so many rules to learn. Can you think of a disadvantage?

    Grandad
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Compute Trig Function Values, Solve Trig Equation
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: September 8th 2011, 08:00 PM
  2. Replies: 7
    Last Post: April 15th 2010, 09:12 PM
  3. Replies: 6
    Last Post: November 20th 2009, 05:27 PM
  4. Replies: 1
    Last Post: July 24th 2009, 03:29 AM
  5. Trig Equations with Multiple Trig Functions cont.
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: April 7th 2008, 06:50 PM

Search Tags


/mathhelpforum @mathhelpforum