<p>I need help with these trigonometric proofs (blah! it'd help if I paid attention in class). ASAP please! =]</p>
<p>Prove that:
1) sinxtanx=secx-cosx</p>
<p>2) (csc(x)^4)-(cot(x)^4)=2(csc(x)^2)-1</p>
<p>Sorry about clarity for number two. It reads like csc4x-cot4x=2csc2x-1, with both 4s and the second 2 being exponents.</p>
<ol>
<li>(1/cosx)+(cosx)= (((cosx)^2)+1)/cosx) = ((1-(sinx)^2)+1)/cosx) = ((sinx)^2)/cosx = (sinx/cosx)(sinx) = (tan x)(sin x)</li>
</ol>
<p>here's # 1:
<a href="http://putfile.com/pic.php?pic=4/11315300587.jpg&s=x402%5B/url%5D">http://putfile.com/pic.php?pic=4/11315300587.jpg&s=x402</a>
I forgot how to do # 2, sorry</p>
<p>Thanks! </p>
<p>Anyone have #2?</p>
<ol>
<li> csc4x-cot4x=2csc2x-1<br>
(1-cos4x)/sin4x
(1-cos2x)(1+cos2x)/sin4x
sin2x(1+cos2x)/sin4x
(1+cos2x)/sin2x
(1+1-sin2x)/sin2x
(2-sin2x)/sin2x
(2/sin2x)-(sin2x/sin2x)
2csc2x-1</li>
</ol>
