Question 694247
{{{ sec x - cosx = 1/cosx - cosx }}}
{{{ sec x - cosx = (1- cos^2(x))/cosx }}}
{{{ sec x - cosx = sin^2(x)/cosx }}}
{{{ sec x - cosx = (sinx sinx)/cosx }}}
{{{ sec x - cosx = sinx tanx) }}} QED