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trigonometry help please!!?

6 tan x - sec^2 x = 7

any help really appreciated :)

3 Answers

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  • ?
    Lv 4
    1 decade ago
    Favorite Answer

    6 tan x - sec^2 x = 7

    6tanx - (1+tan^2x) =7

    6tanx -1 -tan^2x =7

    tan^2x -6tanx +8 = 0

    (tanx-2)(tanx-4) = 0

    tanx=2 ; tanx = 4

    key angle

    63.4 ; 76.0

    tan positive is found in the 1st & 3rd qudrant

    for tanx =2

    x = 63.4, (180+63.4)=243.4

    for tanx =4

    x= 76, (180+76) = 256

    x=63.4, 76, 243.4, 256

    here i'm assuming x is between 0 & 360

  • ?
    Lv 6
    1 decade ago

    You need to give us a little more on the range/ domain of your problem

    The quadratic becomes :

    tan(x) ^2 -6tan x + 8

    so tan x = 4 or tan x = 2

    this gives x = about 76° and 63.4° ( appriox )

    now do you want it in degrees ? Radians ?? first quadrant only ? all values from 0 to 360° ? The general formula ?

    add some detail, and one of us can finish this problem.

    Source(s): Retired Math Teacher
  • 1 decade ago

    replace sec^2 x by 1 + tan^2 x

    and put tanx = t

    solve the quadratic for t

    then put tanx equal to those solutions of quadratic equation

    get the desired value of x

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