Given that point O is any point in equilateral triangle ABC, connect OA and extend to e, so that AE = OA Taking OB and OC as adjacent sides, make parallelogram obfc and connect EF BC.EF= Root 3bC

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1. (1) Given that point O is any point on the plane of equilateral triangle ABC, connect OA and extend to e such that AE = OA with OB.OC Make a parallelogram obfc for the adjacent edge and connect EF. Please explore the quantitative relationship between EF and BC. (2) Given that point O is any point on the plane of the isosceles right triangle ABC (BC is the hypotenuse), connect OA and extend to e, so that AE = OA. Take ob.oc as the adjacent side, make a parallelogram obfc, connect EF. Then the quantitative relationship between EF and BC is () (3) given that point O is any point on the plane of right triangle ABC (BC is the hypotenuse), connect OA and extend it to e, so that AE = OA, and connect EF with OB and OC as parallelogram obfc. Please explore the quantitative relationship between EF and BC.
2. If point O is the outer center of triangle ABC and OA + ob + CO = 0, then what is the inner angle c,
3. E. B and C are on the same straight line, Ba bisects ∠ EBD, ∠ DBC = 30 °. Calculate the degree of ∠ ABC
4. As shown in the figure, let △ ABC and △ CDE be equilateral triangles, and ∠ EBD = 62 °, then the degree of ∠ AEB is () °
5. As shown in Fig. 12.1-6, △ ABC ≌ △ EBD is known, and it is verified that ∠ 1 = 2
6. It is known that, as shown in the figure, ∠ ABC = ∠ DCB, BD and Ca are bisectors of ∠ ABC and ∠ DCB respectively
7. As shown in the figure, triangle ABC is equal to triangle def, angle a = angle D, angle B = angle e, ab = 3, BC = 4, triangle def perimeter is 9.5, point C is the midpoint of DF, find the length of CF
8. In △ ABC, ∠ BAC: ∠ ACB: ∠ ABC = 4:3:2, and △ ABC ≌ △ def, then ∠ def=______ Degree
9. As shown in the figure, triangle ABC is equal to triangle def. Angle a = 50 ° and angle e = 20 ° find angle B and angle def
10. If the inscribed circle O of the triangle ABC and the tangent points of the three sides of the triangle are D, e and f respectively, then what is the center of the triangle def
11. It is known that: as shown in the figure, ∠ ABC = ∠ DCB, BD and Ca are bisectors of ∠ ABC and ∠ DCB respectively, BD and Ca intersect at o Although a little mistake, but also thank you very much!
12. Let o be the heart of the triangle ABC and AO intersect BC with D. if BC = A and the circumference of the triangle ABC is l, then a and L are used to express the ratio AO / OD=
13. The double length method of the central line of congruent triangle: ad is the central line of triangle ABC, e and F are on AB and AC respectively, and De is perpendicular to DF, then what is the relationship among be, CF and ef?
14. As shown in the figure, points B, D, C, f are on a straight line, ab = De, angle a = angle D, AC is parallel to DF, prove 1, triangle ABC is equal to def 2, be = CF
15. Given; point b.e.c.f is on the agreed line, ab = De, angle a = angle D, AC bisects DF; triangle ABC congruent triangle def, be = CF
16. It is known that ab ‖ De, BC ‖ EF, D, C are on AF, and ad = CF
17. As shown in the figure, triangle ABC is equal to triangle def, and angle a is equal to 52%, angle B = 31.21'ed = 1ocm
18. Given △ ABC ≌ △ def, and ∠ a = 52 & # 186;, ∠ B = 31 & # 186;, ed = 10cm, if ∠ f = ∠ C, find the degree of ∠ F and the length of ab
19. Given △ ABC ≌ △ def, and ∠ a = 52 °, B = 31 °, de = 10cm, if ∠ f = ∠ C, find the degree of ∠ F and the length of ab
20. If △ ABC ≌ Δ DEF is known, and the maximum angle of △ ABC is 100 °, then the maximum angle of △ DEF is______ ．