Sunday, October 18, 2009

Stephen's Reflection 9

Ok this week we got into trig. Im not to excited about that because of what ive heard from last year but it seems easy right now. So ill talk about the stuff on 7.2. There are 3 different formulas for this stuff: s=r(theta) , K=1/2 r^2(theta), and k=1/2rs where s= the arc lenght, r=radius, theta=angle, and k=area of circle. Now these involve word problems so its all about figuring out what is s, k, theta, and r. And once that happens, you just plug in and solve. And you cant use all these formulas because sometimes they only give u k, r and theta or s r and theta so you have to figure out which formula you have to use.

I understand alot about these two sections but i know i will forget how to convert degrees and stuff to radius. But what i could use help in is how to make it into minutes or seconds so ill be happy if someone helps.

3 comments:

  1. Finding both minutes and seconds isnt a hard task
    here are some sinple notes that should help

    To find minutes
    multiply what is behind the decimal by 60
    and take whole number as minutes'


    To find seconds
    multiply what is behind the decimal of minutes by 60
    thenmultiply whats behind that decimal by 3600 to get seconds'

    SOMETHINGS YOU NEED TO KEEP IN MIND ARE
    ((***Remember to always ues exact answers))
    ((*** Remember to never plug pi into calculator, instead use the pi button on calculator)

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  2. In addition to the method that Taylor covered above for converting decimal minutes to degrees-minutes-seconds, you could also use your calculator (using the TI-84 Plus Keypad):

    1. Type in your decimal minutes
    2. Press 2nd>Apps to access the Angle menu.
    3. Select option 4.

    I have a tutorial on how to do this for my blog post.

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  3. Conversions:

    Degrees to Radians is: degrees*pi/180
    Radians to Degree is: radians*180/pi

    EXAMPLE: Convert to radians.

    1.) 225 degrees
    225 X pi/180
    225/180 pi
    45/36 pi
    = 5/4 pi

    2.) 30 degrees
    30 X pi/180
    30/180 pi
    = 1/6 pi

    Convert to degrees.

    1.) 3/4 pi
    3/4 pi X 180/pi
    the pi cancels out
    540/4
    = 135 degrees

    2.) pi/6
    pi/6 X 180/pi
    the pi cancels out
    180/6
    = 30 degrees

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