Results 1 to 4 of 4

Math Help - Trigonometry Problems

  1. #1
    Newbie
    Joined
    May 2008
    From
    I live in Green Bay, Wisconsin
    Posts
    3

    Trigonometry Problems

    Here are a few Trig problems that I am having trouble with. Any help is greatly appreciated...


    -Andrew

    1. How many times more intense is a 7.1 richter earthquake than a 6.2 richter quake.
    R = log (I/O)

    2. Evaluate the value of each indicated trig function (SHOW ALL WORK). I can do this one, but I always forget to show all of my work...

    If cos(B) = 4/5, and 3pi/2 < B < 2pi... Find Cot(-B), Cos(2B), and sin(2B)

    3. Answer the question by decoding the message, Show all work...
    What was trig?
    Message encoded using A= [2 5]
    1 3
    38,105,23,69,21,62,20,60,21,55,2,6,29,82,40,100,36 ,93,20,60,31,84,29,82
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78
    Quote Originally Posted by Liquidpyro911 View Post
    Here are a few Trig problems that I am having trouble with. Any help is greatly appreciated...


    -Andrew

    1. How many times more intense is a 7.1 richter earthquake than a 6.2 richter quake.
    R = log (I/O)
    We need to solve the above equation for intensity

    10^R=\frac{I}{O} \iff I =O \cdot 10^R

    Now pluging in our values gives

    I_1=O \cdot 10^{7.1}

    I_2=O \cdot 10^{6.2}

    Now we divide the two

    \frac{I_1}{I_2}=\frac{O \cdot 10^{7.1}}{O \cdot 10^{6.2}} \approx 7.94

    Please show us what you have tried for the other two.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    May 2008
    From
    I live in Green Bay, Wisconsin
    Posts
    3
    I finished #2, but I just have no idea how to do number 3...

    Thanks for the help with the first one... btw...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor Reckoner's Avatar
    Joined
    May 2008
    From
    Baltimore, MD (USA)
    Posts
    1,024
    Thanks
    75
    Awards
    1

    Smile

    Quote Originally Posted by Liquidpyro911 View Post
    I finished #2, but I just have no idea how to do number 3...

    Thanks for the help with the first one... btw...
    I'm assuming the matrix for number 3 is

    \left[\begin{array}{cc}<br />
2 & 5\\<br />
1 & 3<br />
\end{array}\right].

    It seems to me that the message was encoded using this simple algorithm:

    1. Convert all letters to numerical values, with 0 = space, 1 = A, 2 = B, etc
    2. Store each pair of values in a 12 row matrix
    3. Multiply each uncoded row matrix on the right by A to form a coded row matrix
    4. List the values in the coded row matrices, in order and without the matrix notation, to form the coded message

    All you have to do is repeat this process in reverse (hint: you will need to find A^{-1}).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. trigonometry problems help please
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: February 7th 2010, 09:27 AM
  2. Trigonometry problems...
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: September 3rd 2008, 04:43 PM
  3. trigonometry problems
    Posted in the Trigonometry Forum
    Replies: 9
    Last Post: August 16th 2008, 08:41 PM
  4. trigonometry problems
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: July 7th 2008, 05:05 PM
  5. Two Trigonometry Problems
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: March 1st 2007, 12:05 PM

Search Tags


/mathhelpforum @mathhelpforum