It is known that, as shown in the figure, in triangle ABC de / / BC, and the area of triangle ABC is equal to the area of trapezoid bced, the ratio of De to BC is calculated

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• 1. As shown in the figure, in RT △ ABC, the area sum of square Adec and square bcfg is () A. 150cm2b. 200cm2c. 225cm2d. Unable to calculate
• 2. As shown in the figure, make a square from the three sides of RT △ ABC. If the side length of the largest square is 8cm, then the sum of the areas of square m and square n is______ cm2．
• 3. It is known that a [0, a], [b, 0], [C, 0] are the three vertices of △ ABC. A straight line L passing through the origin o of the coordinate intersects with the line AB at point D, and is the extension of ca (1) if the angle BOD is 45 °, calculate the degree of BPD
• 4. As shown in Figure 6, in the plane rectangular coordinate system, the three vertices of △ ABC are a (m, 4) B (6,0) C (- m, - 4), and AC passes through the origin o, BH is perpendicular to AC and H Find the value of AC * BH () to get the positive solution and offer a reward of 40
• 5. It is known that G is the center of gravity of the triangle ABC and O is any point in the plane
• 6. The plane passes through the center of gravity of the triangle ABC, B and C are on the same side of the plane, and a is on the other side of the plane, If the distances from a, B and C to the plane are a, B and C respectively, then the relationship between a, B and C is
• 7. As shown in the figure, ad is the angular bisector of ∠ cab, de ‖ AB, DF ‖ AC, EF intersects ad at point O. excuse me: (1) is do the angular bisector of ∠ EDF? If so, please prove it; if not, please explain the reason. (2) if the conclusion is exchanged with any of the conditions in which ad is the angular bisector of cab, de ‖ AB, DF ‖ AC, is the proposition correct?
• 8. As shown in the figure, in triangle ABC and triangle def, Ag and DH are respectively high, and ab = De, Ag = DH, ∠ BAC = ∠ EDF
• 9. It is known that in △ ABC and △ def, ab = De, BC = EF, ∠ BAC = ∠ EDF = 1000;
• 10. (1) It is known that in △ ABC and △ def, ab = De, BC = EF, ∠ BAC = ∠ EDF = 100?: in △ ABC ≌ △ def (2), if the condition is changed to ab = De, BC = EF, ∠ BAC = ∠ EDF = 70?, is it still true
• 11. As shown in the figure, fold a triangular piece of paper ABC along De, and point a falls inside the quadrilateral bced (1). If ∠ a = α, find ∠ 1 + 2
• 12. (1) As shown in the figure, the triangle ABC paper is folded along De to form figure 1. At this time, point a falls inside the quadrilateral bced, and there is a quantitative relationship between angle A and angle 1 and angle 2, which remains unchanged. Find out the quantitative relationship and explain the reason; (2) If the point a falls on be or CD, write the relationship between angle A and angle 2, angle A and angle 1, and explain the reason; (3) If folded into Figure 4, write the relationship between angle A and angle 1, angle 2, and explain the reason; (3) if folded into figure 5, write the relationship between angle A and angle 1, angle 2, and explain the reason
• 13. As shown in the figure, fold the △ ABC paper along de. when point a falls inside the quadrilateral bced, try to explore,
• 14. As shown in the figure, in △ ABC, ∠ C = 90 °, D is the point on AC, de ⊥ AB is at point E. if AB = 10, BC = 6, de = 2, calculate the area of quadrilateral DEBC
• 15. As shown in the figure, in △ ABC, ∠ C = 90 ° de bisects AB vertically, intersects BC with E, ab = 20, AC = 12. (1) find the length of be; (2) find the area of quadrilateral Adec
• 16. It is known that in ABC triangle, D and E are AC = 7, ∠ ABC = 120 °, AE = BC and Sina = 3 √ 3 / 14 on AC and ab respectively, and the area of quadrilateral DEBC is calculated Please, the sooner the better,
• 17. In triangle ABC, D and E are the midpoint of AB and AC respectively, then the area ratio of triangle ade to quadrilateral DEBC is ()
• 18. The circumference of circle O is equal to 4 π cm. Find the side length, side center distance and area of its inscribed regular triangle ABC
• 19. The perimeter sum of an equilateral triangle ABC and a square defg is 95 decimeters. AB: de = 1:4. What is the side length of an equilateral triangle
• 20. As shown in the figure, the triangle ABC is a right triangle, the quadrilateral EDFC is a square, the sum of the areas of the two shadow triangles is 32 square centimeters, ad: DB = 4:1, find the length of AD