left = cosx( 1+secx+tanx)/cosx( 1+secx-tanx)

=(cosx+ 1+sinx)/(cosx+ 1-sinx)=(cosx+ 1+sinx)^2/[(cosx+ 1)+sinx)][(cosx+ 1)-sinx]

=2( 1+cosx+sinx+sinxcosx)/[(cosx+ 1)^2-(sinx)^2]

=2( 1+sinx)( 1+cosx)/[(cosx+ 1)^2-( 1+cosx)( 1-cosx)]

= 2 (1+sinx)/(cosx+1-1+cosx) = (1+sinx)/cosx = right,

So the conclusion is established;

2. Because when cosx=- 1, the terminal edge of X falls on the negative semi-axis of X axis and does not belong to any quadrant.