Re: area

Posted by T.Gracken on October 22, 2002 at 07:44:49:

In Reply to: Re: area posted by Helen on October 21, 2002 at 18:21:42:

: : what have you tried already?
: : I am not going to attempt an answer for this without more info on what you have attempted and why. This is too extensive a problem to explain without more info!

: I'm stuck after getting this far:

: Sin(x+y)Cos(y) >= Sin(x)

: Sin(x)Cos(y)Cos(y) + Cos(x)Sin(y)Cos(y) - Sin(x) >= 0

: Sin(x)(Cos(y)Cos(y) - 1) + Cos(x)Sin(y)Cos(y) >= 0

you still haven't answered any of my questions... so if you just want to manipulate the expression, how about this:

Sin(x)(Cos(y)Cos(y) - 1) + Cos(x)Sin(y)Cos(y) >= 0 {your last step}

=> Sin(x)(Cos(y) - 1) + Cos(x)Sin(y)Cos(y) >= 0

=> Sin(x)(1 - Sin(y) - 1) + Cos(x)Sin(y)Cos(y) >= 0

=> -Sin(x)Sin(y) + Cos(x)Sin(y)Cos(y) >= 0

=> Sin(y)[Cos(x)Cos(y) - Sin(x)Sin(y)] >= 0

=> Sin(y)Cos(x+y) >= 0

Although I don't know where that will lead you (yet).

By the way; This is a very complex problem. Are you sure you copied it correctly (and entirely)? Including the directions? Have you studied surfaces and/or parametric equations? The more I look at the problem you wrote, the more I tend to believe there is something you haven't told us.

Follow Ups:

• sorry, lots of missing tags. try this one T.Gracken 10:13:56 10/22/02 (3)
  • here's the solution, THANKS LOTS for the help! Helen 20:47:06 10/22/02 (2)
    • Re: here's the solution, THANKS LOTS for the help! T.Gracken 12:02:24 10/23/02 (0)
    • I don't understand... Joel 22:22:29 10/22/02 (0)

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