The crossing point e is ef⊥ad, e is on the bisector of ∠adc, ec⊥cd, ef⊥ad, so ec=ef, and because ed is a public * * * side, so △edc and △edf are congruent (hl).

Because E is the midpoint of cb, ec=eb, and it has been proved before that ec=ef, so eb=ef, ae is the same side, and it is proved that △aef and △abf are congruent, and it is deduced that ∠eab=∠eaf, ∠ced=35 degrees, then ∠ CDE =

Because de is the bisector of ∠adc, ∠adc= 1 10 degrees.

∠c=∠b=90 degrees, and cd is parallel to ab, so∠ ADC +∠ DAB =180 degrees, so∠ ∠dab=70 degrees.

It has been proved that ae is the bisector of ∠dab, so ∠eab=35 degrees.

Extended data:

Congruent triangles's judgment method is a very important part of our study of junior high school mathematics and geometry, and it is also a necessary test point for senior high school mathematics.

It is mainly through conditional analysis to prove the congruence of two triangles. The conditions are different, so we use different methods to judge.

Today, I will explain the contents and skills of congruent triangles's judgment methods one by one, so as to help you really master the skills of using the five judgment methods, enhance your full understanding of geometry and improve the application efficiency of knowledge in practical applications.

SSS: When learning congruent triangles's judgment rules, the first rule is edge and edge, which is also the simplest rule in congruent triangles's judgment process. It is a basic problem in practical application that the three sides of two triangles should be equal respectively, which is not difficult.

Two triangles with three equal sides are congruent. That is to say, if the length of three line segments is given (satisfying the triangle trilateral relationship), the shape and size of the triangle can be determined.

Specifically, we will fully understand how congruent triangles's judgment was obtained through the following steps, and the way to understand this method is what Mr. Tang has fully explained in the previous article.