<p>this problem is weird... i don't get why the right side is cos2x-cos2x??</p>
<p>Prove that:</p>
<p>sinxsecx/(tanxcotx) = cos2x-cos2x</p>
<p>Doesn't the right side just equal tanx?</p>
<p>I think the left side is equal to tan too. The denominator would cancel: tan times cot=1. Sin times sec=tanx because sec=1/cos and thus sin/cos=tan.</p>
<p>i thought the ride side was just 0?</p>
<p>how do you know that cos2x-cos2x = tan?</p>
<p>yeah i think it is 0...are you sure you typed the problem correctly? the left side is tan though</p>
<p>i thought thats what was on the board... if it were cos 2x + cos 2x would that make it tan x ? maybe i copied down the wrong sign :-/</p>
<p>and we can only manipulate one side of the equation..</p>