As shown in the figure, △ ABC, ab = AC, ad ‖ BC, then ad bisects ∠ EAC, try to explain the reason

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• 1. As shown in the figure, it is known that ∠ B = ∠ C. If ad ‖ BC, does ad divide ∠ EAC equally? Please give reasons
• 2. As shown in the figure, ad is the angular bisector of the outer angle of the triangle ABC. The intersection of AD and the circumscribed circle of the triangle ABC is at point D
• 3. (the third power of 4B / 7 - the square of 7ab + the square of 2B / 5) △ the square of 2B / 5
• 4. If the two vertex coordinates a (- 4,0), B (4,0) of △ ABC and the perimeter of △ ABC are 18, then the trajectory equation of vertex C is___ ．
• 5. Given the vertex a (1,4) of △ ABC, if point B is on the Y axis and point C is on the line y = x, then the minimum perimeter of △ ABC is______ ．
• 6. Given the point a (- 1, - 4), try to take a point B and C on the Y-axis and the line y = x to minimize the perimeter of the triangle ABC, and find the coordinates of B and C
• 7. The perimeter of △ ABC is 16. The end points of the three sides of △ ABC are connected to form a triangle, and then the midpoint of each side of the new triangle is connected to form a second triangle. And so on, the perimeter of the second triangle is 2006 power of A1 / 2 2007 power of B1 / 2 2008 power of C1 / 2 2009 power of D1 / 2
• 8. D. E are the points on the sides AB and AC of triangle ABC. Triangle ABC and triangle ade are similar triangles. If ad = 2cm, ab = 3cm, AC = 4cm, find the length of AE
• 9. As shown in the figure, in the angle ABC, the angle c = 90 degrees, D and E are the points on AB and AC respectively, and ad · AB = AE · AC, then ed Is it perpendicular to ab? Please explain why
• 10. In the triangle ABC, the angles C = 90 °, D and E are the points on AB and AC respectively. Ad times AB = AE times AC, it is proved that ED is perpendicular to ab C: [documents and settings] administrator [desktop] unnamed.jpg
• 11. It is known that ad is the bisector of the outer angle EAC of △ ABC, and ad ‖ BC, then the edge of △ ABC must satisfy______ ．
• 12. BD bisects ∠ ABC, be divides ∠ ABC into two parts of 3:4, ∠ DBE = 8 degrees, and calculates the degree of ∠ ABC
• 13. BD bisects the angle ABC, be divides the angle ABC into 3:5, two parts, the angle DBE is equal to 15 degrees, and finds the degree of the angle ABC
• 14. As shown in the figure, BD bisects ∠ ABC, be bisects ∠ ABC into two parts of 2:5, ∠ DBE = 27 ° and calculates the degree of ∠ ABC
• 15. As shown in the figure, BD is divided into two parts, be is divided into ABC 2:5, DBE = 21 ° and the degree of ABC is calculated
• 16. BD score ∠ ABC, be score ∠ ABC is 2:5, DBE = 21 degrees, calculate the degree of ∠ ABC
• 17. As shown in the figure, ad is the middle line of △ ABC, AE: AC = 1:3, ad intersects be at point F, then the ratio of the area of △ ABC to the area of △ ABF is one
• 18. As shown in the figure, the midlines AD and be of △ ABC intersect at point F. what is the quantitative relationship between △ ABF and the area of quadrilateral cefd? Why?
• 19. As shown in the figure, we know that be ⊥ ad, CF ⊥ ad, and be = cf. please judge whether AD is the middle line of △ ABC or the angular bisector? Please state the reason for your judgment
• 20. As shown in the figure, in △ ABC, ab = AC, ad ⊥ BC at point D, point E on AC, CE = 2ae, ad = 9, be = 10, ad and be intersect at point F, then the area of △ ABC is______ ．