As shown in the figure, ad is the angular bisector of △ ABC, de ‖ AB, DF ‖ AC, EF intersects ad at point O. excuse me: is do the angular bisector of △ def? Please give reasons

Do is the angular bisector of △ def. It is proved that: ∵ ad is the angular bisector of △ ABC, ∵ CAD = ∵ bad. ∵ de ∥ AB, DF ∥ AC, ∵ EDA = ∵ fad, ∵ FDA = ∵ ead, ∵ EDA = ∵ FDA. ∵ do is the angular bisector of △ def

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1. As shown in the figure, ad is the angular bisector of angle cab, ed | AB, DF | Ca, EF intersects ad at point O. excuse me, (1) is do the angular bisector of angle EDF? If so, give a clear proof;
2. As shown in the figure, AC ', BD', Ca ', DB' are bisectors of the four inner angles of the planar quadrilateral ABCD Please find out all the parallelograms except for the parallelogram ABCD. No more letters will be added and one of them will be selected to prove that although we didn't learn 5.2 parallelograms from the figure,
3. It is known that in △ ABC, ad is the bisector of ∠ BAC outer angle ∠ EAC, and D is the intersection of bisector and BC extension Don't copy the answer
4. As shown in the figure, in the quadrilateral ABCD, ab ‖ CD, AE bisection ∠ bad intersects BC at point E, and ab = EB is proved. The quadrilateral ABCD is a parallelogram
5. It is known that the quadrilateral ABCD is a parallelogram, the bisector CF of ∠ BCD intersects AB at F, and the bisector DG of ∠ ADC intersects AB at G 1. Verification: AF = GB 2. Please add another condition on the basis of the known condition, so that Δ EGF is an isosceles right triangle
6. As shown in the figure, in △ ABC, D is the point on AC, e is the point on CD extension line, and AC / BC = EF / DF, verification: ad = EB
7. In the known triangle ABC and triangle def, ab = 2 cm, BC = 3 cm, CA = 4 cm, de = 7.5 cm, EF = 10 cm, FD = 5 cm Like? Why?
8. Take a pair of triangle ruler and splice it according to the way shown in Fig. 1, fix the triangle ruler ADC, and rotate the triangle ruler ABC clockwise around point a to get the triangle ruler Let's ask when α is how many degrees, can make ab ‖ DC? 2 rotate to the position of ③, then how many degrees is α?
9. As shown in the figure, the hypotenuse ab of the right angle triangle plate ABC is 12cm, ∠ a = 30 °, rotate the triangle plate ABC clockwise 90 ° around C to the position of triangle plate a'b'c ', and then translate it to the left along the CB direction, so that the point B' falls on the hypotenuse ab of the original triangle plate ABC, then the translation distance of triangle plate a'b'c 'is () A. 6cmB. 4cmC. （6-23）cmD. （43−6）cm
10. As shown in the figure, △ EBD is obtained by turning the right triangle ruler ABC with 30 ° angle clockwise 150 ° around point B and connecting CD. If AB = 4cm, the area of △ BCD is () A. 43B. 23C. 3D. 2
11. As shown in the figure, △ ABC is all equal to △ ade, ∠ bad = 28 ° to get the degree of ∠ EAC
12. As shown in the figure, if △ ABC ≌ △ ade, ∠ EAC = 30 °, then ∠ bad=______ Degree
13. As shown in the figure, point D is on the side BC of △ ABC, ∠ abd = ∠ ade, ∠ bad = ∠ CDE = ∠ EAC As shown in the figure, point D is on the side BC of △ ABC, ∠ ADB = ∠ ade, ∠ bad = ∠ CDE = ∠ EAC
14. If M is known to be the center of gravity of the triangle ABC, then the vector am + BM + cm =?
15. It is known that the three vertices of the triangle ABC are a (1,2) B (4,1) C (3,4). How to find the length of the central line cm on the edge of AB? (with vector solution) is urgent!
16. In the triangle ABC, B (- 3,0). C (3,0). If the inscribed circle is x ^ 2 + y ^ 2-4x-2ky + 4 = 0, then the trajectory of vertex A is
17. If vertex a (- 5,0), B (5,0) of △ ABC and the center of the inscribed circle of △ ABC are on the straight line x = 3, then the trajectory equation of vertex C is______ ．
18. Given the coordinates of the three vertices of the triangle 2.11.03.0, the sine value of the ball angle B and the area of the triangle
19. Given that the vertices of triangle ABC are a (1,2). B (2,3). C (- 2,5), then what kind of triangle is a triangle? A right angle, B acute angle, C Angle, not above D It's better to have an analysis process
20. In △ ABC, the opposite sides of angles a, B and C are a, B and C respectively, and satisfy 2bcosa = ccosa + acosc. (1) find the size of angle a; (2) if a = 3 and s △ ABC = 334, try to judge the shape of △ ABC and explain the reason