If point O is the outer center of triangle ABC and OA + ob + CO = 0, then what is the inner angle c,

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• 1. E. B and C are on the same straight line, Ba bisects ∠ EBD, ∠ DBC = 30 °. Calculate the degree of ∠ ABC
• 2. As shown in the figure, let △ ABC and △ CDE be equilateral triangles, and ∠ EBD = 62 °, then the degree of ∠ AEB is () °
• 3. As shown in Fig. 12.1-6, △ ABC ≌ △ EBD is known, and it is verified that ∠ 1 = 2
• 4. It is known that, as shown in the figure, ∠ ABC = ∠ DCB, BD and Ca are bisectors of ∠ ABC and ∠ DCB respectively
• 5. 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
• 6. In △ ABC, ∠ BAC: ∠ ACB: ∠ ABC = 4:3:2, and △ ABC ≌ △ def, then ∠ def=______ Degree
• 7. 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
• 8. 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
• 9. If the inscribed circle of triangle ABC and the tangent points of three sides are D, e and f respectively, the triangle def must be an acute triangle Why?
• 10. Circle O is the inscribed circle of triangle ABC, D, e and F are the tangent points. What are the characteristics of the shape of triangle def? Please explain the reasons
• 11. (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.
• 12. 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
• 13. 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!
• 14. 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=
• 15. 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?
• 16. 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
• 17. 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
• 18. It is known that ab ‖ De, BC ‖ EF, D, C are on AF, and ad = CF
• 19. 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
• 20. 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