教我怎么做这题---**Problem:** 19. 如图, 在△ABC 中, AD ⊥ BC, AE 是 BC 边上的中线, AB = 10, AD = 6, tan∠ACB = 1. (1) 求 BC 的长; (2) 求 sin∠DAE 的值. **Translation of Problem Statement:** 19. As shown in the figure, in △ABC, AD ⊥ BC, AE is the median to side BC, AB = 10, AD = 6, tan∠ACB = 1. (1) Find the length of BC; (2) Find the value of sin∠DAE. **Geometric Figure Description:** * **Type:** Triangle ABC with two line segments AD and AE drawn from vertex A to side BC. * **Points:** Vertices A, B, C of the triangle. Points D and E lie on the side BC. * **Lines/Segments:** AB, AC, BC, AD, AE. * **Relative Positions:** Points B, E, D, C are collinear along a horizontal line segment representing side BC. A is a vertex above the line BC. D and E are points on BC between B and C. D is located between E and C. * **Relationships:** * AD is perpendicular to BC (indicated by AD ⊥ BC in the text and implicitly by the vertical line AD meeting the horizontal line BC in typical diagrams, though no explicit right angle symbol is present in the drawing). Point D is the foot of the altitude from A to BC. * AE is the median to BC. This means E is the midpoint of BC. * **Labels:** Points are labeled A, B, C, D, E. Side lengths AB=10, AD=6 are given in the text. The angle ∠ACB is relevant as its tangent is given. The angle ∠DAE is the angle whose sine is to be found.