Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Mathematics (https://www.askmehelpdesk.com/forumdisplay.php?f=199)
-   -   Solving trigonometric equations (https://www.askmehelpdesk.com/showthread.php?t=149434)

  • Nov 7, 2007, 07:23 AM
    helpless06
    Solving trigonometric equations
    Prove:
    sin^3 X+cos^4 X=1

    Here is what I have done so far:
    Prrof:
    sin^3x+cos^4x=1
    sin^3x=1-cos^4x
    sin^3x=(1-cos^2x)(1+cos^2x)
    sin^3x=sin^2x(1+cos^2x)
    sin^3x-[sin^2x(1+cos^2x)]=0
    sin^2x[sinx-1(1+cos^2x)]=0

    I do not know where to go from here or if I am on the right track... help.
  • Nov 7, 2007, 10:49 AM
    terryg752
    Are you sure that the question is:

    Prove:
    sin^3 X+cos^4 X=1?

    It is clear to me that you have read the question incorrectly.

    May be the question is:

    SOLVE: sin^3 X+cos^4 X=1

    The above equation is not correct for all values of X.

    The only way above equation can be true is if

    Sin x = 1 or sin x = 0

    Which is possible, e.g. if x = pi/2 or x = 0

  • All times are GMT -7. The time now is 01:43 AM.