mwilt Posts: 3, Reputation: 1 New Member #1 Mar 4, 2009, 03:04 PM
trigonometry proofs
how do you prove that

tanx+coty / tanxcoty = tany+cotx
 galactus Posts: 2,271, Reputation: 282 Ultra Member #2 Mar 4, 2009, 03:50 PM
$\frac{tan(x)+cot(y)}{tan(x)cot(y)}$

This only requires about one step.

Expand it out and look at the cancellations.

$\frac{tan(x)}{tan(x)cot(y)}+\frac{cot(y)}{tan(x)co t(y)}$

See it?
 mwilt Posts: 3, Reputation: 1 New Member #3 Mar 4, 2009, 08:52 PM

Thank you! I get it now!
 cazey Posts: 1, Reputation: 1 New Member #4 Jun 9, 2009, 07:01 PM

how do I prove that sin20=x/8?
 Perito Posts: 3,139, Reputation: 150 Ultra Member #5 Jun 9, 2009, 07:42 PM

$sin(20)=\frac {x}{8} ?$

That looks more like an equation than a proof.

$x=8 sin(20) \approx 2.736$

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