Determine the quadrant

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mattmurdock

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Apr 12, 2007
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Thank God I found this forum! Can someone explain to me how I can aproach this?

Determine the quadrant in which angle x lies, when sin x < 0 and cos x < 0.

Matthew
 
Hello Matt. Welcome.

Here's something to get familiar with. You can see for yourself. :D

unitcirclesmallhg1.gif
 
Hello Galactus and thank you! (I look forward to seeing you in the new FF4 movie--lol:))
I've seen this...how do I use it to find the solution?
 
the coordinates of each point on the unit circle are in the order ...

\(\displaystyle \L (\cos{\theta}, \sin{\theta})\)

look for the quadrant where sine and cosine are both negative.
 
that section of the unit circle is known as quadrant III ... where \(\displaystyle \L \theta\) satisfies the following inequality ...

\(\displaystyle \L \pi < \theta < \frac{3\pi}{2}\)
 
I look forward to seeing you in the new FF4 movie
Click to expand...

Is the galactus character going to be in the new FF4 movie?. I never heard. All I heard about was the Silver Surfer.
 
So the answer is in solving the inequalities?

sinx<0=

x<sin^(-1)(0)

x<0

x=pi+0

x=pi

x=0,pi


cosx<0=

x<cos^(-1)(0)

x<(pi)/(2)

x=(3pi)/(2)

x=(pi)/(2),(3pi)/(2)

??
 
galactus said:
I look forward to seeing you in the new FF4 movie
Click to expand...

Is the galactus character going to be in the new FF4 movie?. I never heard. All I heard about was the Silver Surfer.
Click to expand...

this is the plot outline from imdb.com:

"The Fantastic Four learn that they aren't the only super-powered beings in the universe when they square off against the powerful Silver Surfer and the planet-eating Galactus."
 
sin and cos are both less than 0 between pi and 3pi/2. The unit circle tells it all.
 
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