(1-sinx)/cosx=[sin²(x/2)+cos²(x/2)-2sin(x/2)cos(x/2)]/[cos²(x/2)-sin²(x/2)]=[cos(x/2)-sin(x/2)]²/{[cos(x/2)+sin(x/2)]*[cos(x/2)-sin(x/2)]}=[cos(x/2)-sin(x/2)]/[cos(x/2)+sin(x...