大学选修课论文有这个的参考下吧

Proposition 3: vertical angles equal

Proof: a straight line AB, CD intersect at point E

∵ < DEA + < CEA = < CEA + < BEC = 180 ° (proposition 2)

∴ < DEA = < BEC

Proposition 4: two straight line parallel,

TongWeiJiao equal

A linear EF and two parallel straight line AB, CD intersect Hypothesis is not equal to < GHD AGH < Might as well put < AGH larger < AGH + < BGH > < GHD + < BGH

And < AGH + < BGH = 180 ° (proposition 1) ∴ < GHD + < BGH < 180 °

∴ two straight line extension will intersect And two straight line parallel ∴ < AGH = < GHD

And < AGH = < EGB (proposition 3) ∴ < GHD = < EGB