# Trigonometry - quick question

1. May 11, 2005

### DivGradCurl

I have a straight-forward question. Could anybody please explain me why...

$$\theta = \tan ^{-1} \left( \frac{x}{2} \right) \Rightarrow -\frac{1}{4\sin \theta} = -\frac{\sqrt{x^2+4}}{4x}$$

Thanks

2. May 11, 2005

### whozum

Draw a triangle. Your vertical side will be x, your horizontal base will be 2. This is directly from the tan function. From there you can use pythagorean theorem to find the hypotenuse. Now you have all three sides, and you're trying to find

$$-4csc(\theta)$$. Just pull it right off the triangle. CSC is hyp/opp.

3. May 11, 2005

### DivGradCurl

One sec. after I posted it I realized what to do. Thanks, anyway.

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