Re: HSC 2013 2U Marathon
i took a common factor of secx
if your talking about the change from cos to the power of 4 to them two brackets, you use this rule
<a href="http://www.codecogs.com/eqnedit.php?latex=(x^{2}-1)&space;=&space;(x&space;-&space;1)(x+1)" target="_blank"><img...