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Trig Help

  1. Sep 6, 2009 #1
    1. The problem statement, all variables and given/known data

    56. Finding the Height of a Building
    To measure the height of a building, two sightings are taken a distance of 50 feet apart. if the first angle of elevation is 40 degrees and the seconds is 32 degrees, what is the height of the building?

    2. Relevant equations

    defintion of tan theta

    3. The attempt at a solution

    http://img40.imageshack.us/img40/148/asdasdye.jpg [Broken]

    (def of tan theta = a^-1 o)a = o
    opposite = adjacent tan theta

    written with respect to the first angle

    opposite = (adjacent 1 + adjacent 2) tan theta one

    were adjacent 1 is the 50 feet

    written for the second angle

    opposite = adjacent 2 tan theta two

    set them equal to each other

    (adjacent 1 + adjacent 2) tan theta one = adjacent 2 tan theta two

    distripute

    adjacent 1 tan theta one + adjacent 2 tan theta one = adjacent 2 tan theta two

    subtract from both sides

    adjacent 1 tan theta one = adjacent 2 tan theta two - adjacent 2 tan theta one

    factor or whatever

    adjacent 1 tan theta one = adjacent 2 (tan theta two - tan theta one)

    muliply by inverse to solve for adjacent 2

    (adjacent 1 tan theta one = adjacent 2 (tan theta two - tan theta one)) ((tan theta two - tan theta one)^-1

    adjacent two = (tan theta two - tan theta one)^-1 adjacent 1 tan theta one

    plug and chug for adjacent two

    adjacent two = (tan 32 degrees - tan 40 degrees)^-1 (50 ft) tan theta 40 degrees

    I got negative 195.8 feet?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
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