Re: drawing

From: William Elliot (marsh_at_privacy.net)
Date: 01/23/05 

Date: Sun, 23 Jan 2005 05:52:41 -0800

On Sun, 23 Jan 2005, mina_world wrote:

> draw the ordered pair (x,y) in the x-y plane such that
> cosx > (siny)*{sin(x+y)}
>
Let y = 0, x = pi/2

> sorry...i don't know.
> give me good hint, please.
>
Are you wanting to graph or draw the region
         { (x,y) | sin y * sin x+y < cos x } ?
sin y (sin x cos y + cos x sin y) < cos x
sin x sin y cos y + cos x sin^2 y < cos x
sin x sin y cos y + cos x - cos x * cos^2 y < cos x
sin x sin y cos y < cos x cos^2 y

For cos y > 0
         sin x sin y < cos x cos y
For cos y < 0
         sin x sin y > cos x cos y
For cos y = 0,
         sin x sin y = 0

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