由于：cosα>sinα则有：sinα-cosα0tanα(tanα+1)(tanα-1)>0则：tanα属于(1,正无穷)U(-1,0)又：α属于(0,π/4)U(5π/4,2π)则：α属于(5π/4,3π/2)U(7π/4,2π)由于：cotα>cosα则有：cosα/sinα>cosαcosα...