讲解下这道题目---**Question Stem:** 如图在△ABC中，∠BAC=100°，AD⊥BC 于 D，AE 平分∠BAC，∠B=40°，则∠DAE=多少度？ **Mathematical Information & Question:** In triangle ABC, ∠BAC = 100°, AD is perpendicular to BC at D, AE bisects ∠BAC, ∠B = 40°. What is the measure of ∠DAE in degrees? **Chart/Diagram Description:** * **Type:** Geometric figure (Triangle). * **Main Elements:** * A triangle labeled ABC. * Point A is the apex. * Points B and C are on the base line. * A segment AD is drawn from A to the base line, meeting at point D. * A segment AE is drawn from A to the base line, meeting at point E. * Points B, D, E, C are arranged on a horizontal line segment in that order from left to right. * Point A, B, C are marked with red dots. * Points D, E are marked with orange dots. * Triangle ABD and triangle ADC appear to be shaded grey. * Line segment AD is vertical, indicating perpendicularity to the base line BC. * Line segment AE is positioned between AD and AC. * **Labels:** Points A, B, C, D, E are labeled. * **Relationships:** * A, B, C form a triangle. * D and E lie on the line segment BC. * AD is perpendicular to BC. * AE is a line segment from A to the base. * **Angles/Properties depicted:** The figure visually represents the described triangle ABC, the altitude AD, and the angle bisector AE. AD is shown as perpendicular to BC by its vertical orientation relative to the horizontal BC. AE is shown as a line segment dividing angle BAC. The shading suggests the triangle is divided into two parts by AD or some other lines. **Options:** (No options are provided in the image)