Помогите сравнить. Выражение преобразовал и сократил по формулам, а как сравнить???

Решите задачу:

$\frac{1+cos40+cos80}{sin80+sin40}=\frac{1+cos40+cos^240-sin^240}{2sin40cos40+sin40}=\frac{2cos^240+cos40}{2sin40cos40+sin40}=\\=\frac{cos40(2cos40+1)}{sin40(2cos40+1)}=ctg40\\\\\frac{cos105cos5+sin105sin5}{sin95cos5+cos95sin5}=\frac{cos100}{sin100}=ctg100=ctg(180-80)=-ctg80\\ \frac{1+cos40+cos80}{sin80+sin40}\ \textgreater \ \frac{cos105cos5+sin105sin5}{sin95cos5+cos95sin5}$

$\frac{sin20-sin40}{1-cos20+cos40}=\frac{sin20-2sin20cos20}{1-cos20+cos^220-sin^220}=\frac{sin20(1-2cos20)}{-cos20+2cos^220}=\\=\frac{sin20(1-2cos20)}{cos20(-1+2cos20)}=-tg20\\\\\frac{sin25cos5-cos25sin5}{cos15cos5-sin15sin5}=\frac{sin20}{cos20}=tg20\\\frac{sin20-sin40}{1-cos20+cos40}\ \textless \ \frac{sin25cos5-cos25sin5}{cos15cos5-sin15sin5}$