MHB Sinx and cosx in the second quadrant

Thread starter tmt1
Start date Jan 11, 2015

AI Thread Summary

In the second quadrant of the unit circle, sine values are positive while cosine values are negative. Therefore, if sin(x) > 0 and cos(x) < 0, it confirms that angle x is indeed located in the second quadrant. This is because points in this quadrant have positive y-coordinates and negative x-coordinates. Understanding the unit circle is crucial for visualizing these relationships. Thus, the conclusion about the angle's position is valid based on the signs of the sine and cosine functions.

Jan 11, 2015

tmt1

In a question we have sinx > 0 and cosx < 0.

The book says that from this we can determine that angle x is in the second quadrant. I am not understanding this leap.

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Jan 11, 2015

MarkFL

Gold Member

MHB

Think of the unit circle...in which quadrant do points on the circle have negative $x$-coordinates and positive $y$-coordinates?

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