The height of a trapezoid is 7 cm. The product of it and the upper bottom is 78.4, and the product of it and the lower bottom is 178.4. So the area of this trapezoid is______ Square centimeter

(78.4 + 178.4) △ 2 = 256.8 △ 2 = 128.4 (square centimeter); answer: the area of this trapezoid is 128.4 square centimeter

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1. For a trapezoid, the product of its height and upper bottom is 15 square centimeters. The product of its height and lower bottom is 21 square centimeters. What is the area of this trapezoid?
2. The product of the height of a trapezoid and its two bases is 18 square centimeters and 25 square centimeters respectively. What is the area of the trapezoid?
3. The area of the new trapezoid is increased by 76 square centimeter if the bottom is lengthened by 1 / 4 and the height and upper bottom remain unchanged
4. The figure on the right is a trapezoid. If the bottom is extended by one fourth, and the upper bottom and height remain unchanged, the new trapezoid is 76 square centimeters larger than the original trapezoid. Calculate the area of the original trapezoid
5. The ratio of the top to the bottom of a trapezoid is 3 / 5. The top is 1 meter shorter than the bottom, and the bottom is 25% higher. What is the area of this trapezoid?
6. Given the three vertices a (1,2), B (3,4) and C (2,6) of ladder ABCD, find the point direction equation of the straight line where the median line of the ladder is located?
7. Let the vertex coordinates of ladder ABCD be a (- 1,2), B (3,4), D (2,1), and ab is parallel to DC, ab = 2 DC, then the coordinates of point C are obtained AB = 2 DC with arrow (plane vector)
8. If the vertex a (- 1,2) B (3,4) d (2,1) of ladder ABCD and ab ‖ DC, ab = 2CD, then the coordinate of point C is?
9. Vertex a (- 2,2), B (- 1,4), C (4,5 +) of ladder ABCD, and AB / / DC, ab = 1 / 2dc, find the coordinates of vertex D Correction, C (4,5)
10. In rectangular trapezoid ABCD. Ad = 7 & nbsp; & nbsp; ab = 2 & nbsp; & nbsp; DC = 3 & nbsp; & nbsp; P is a point on ad. the triangle with the vertex of P, a and B is similar to the triangle with the vertex of P, D and C. how many such points P have? Why?
11. In the quadrilateral ABCD, e is the point on AB, the triangle ade and BCE are equilateral triangles, and the midpoint of AB and bcbdda are pqmn respectively, so we can judge the quadrilateral of pqmn In quadrilateral ABCD, e is the point on AB, triangle ade and BCE are equilateral triangles, and the midpoint of AB, BC, BD and DA are p, Q, m and N respectively. What kind of quadrilateral is pqmn quadrilateral?
12. In rectangular ABCD, the angle DEA = 30 degrees, e is a point on CD, and AE = AB = 8cm, find (1) the degree of angle EBC; (2) the area of triangle ade
13. As shown in the figure, in isosceles trapezoid ABCD, ad ‖ BC, ∠ B = 60 °, ad = ab. points E and F are on AD and ab respectively, AE = BF, DF and CE intersect at P, then ∠ DPE=______ Degree
14. There is a point P in the square ABCD with side length 2. Find the minimum value of PA + Pb + PC. please write the procedure. 7. Ab There is a point P in the square ABCD with side length 2. Find the minimum value of PA + Pb + PC. please write the procedure 7. AB and AC are the diameter chord of circle O respectively, D is the point on inferior arc AC, De is perpendicular to ab at point h, intersecting circle O at point E, intersecting circle AC at point F, P is a point on extended line of ED
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16. Let p be any point on the inferior arc ad of circumscribed circle of square ABCD, then the ratio of PA + PC to Pb is______ ．
17. It is known that: as shown in the figure, in square ABCD, point E is a point on the side of AD, and the intersection diagonal of CE is BD at point P, PE = AE. (1) verification: CE = 2ed. (2) when Pb = 6cm Please teach me the way I understand, Just a second question
18. As shown in the figure, a point P, PE ⊥ ad in the square ABCD is equal to E. if Pb = PC = PE = 5, then the side length of the square is______ ．
19. The side length of square ABCD is a, PA ⊥ plane ABCD, PA = a, m, n are the midpoint of PD, Pb respectively, then the cosine value of the angle formed by the line am and cn is
20. It is known that P is a point AC on the diagonal of square ABCD (not coincident with a and C), PE is perpendicular to point E, PF is perpendicular to point F 1, and CD is perpendicular to point F 1 It is known that P is a point AC (not coincident with a and C) on the diagonal of square ABCD, PE is perpendicular to point E, PF is perpendicular to point F 1. Verify BP = DP 2. If the quadrilateral PECF rotates counterclockwise around point C, is there BP = DP in the process of rotation? If so, please prove it, if not, please use counter examples Try to select two vertices of square ABCD and connect them with the two vertices of quadrilateral PECF, so that the length of the two segments is equal when the quadrilateral PECF rotates counterclockwise around point C, and prove your conclusion Thank you on your knees