Trapezoid ABCD, M is the waist midpoint of AD, triangle ABM area is 8, triangle MCD is 12, calculate the area of triangle BMC

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• 1. M is a point on parallelogram ad. if the area of parallelogram ABCD is equal to 4 square centimeters, how many square centimeters is the area of triangle MBC equal to?
• 2. A new two digit number is four seventh of the original number What is the original two digit number? How many such two digits are there?
• 3. Solve the equation 2.8x4-5x = 5.8 Solving practical problems with equations Two engineering teams jointly build a 3.9 km long highway, which will be completed in 20 days. It is known that team a builds 0.1 km per day, and team B how many km per day? Xiaoqing and her mother went to the shopping mall to buy two boxes of chocolate, 59.8 yuan per box, and 4.5 kg of candy, 14.6 yuan per kg. How much did they spend?
• 4. What's the difference between arithmetic left shift, logic left shift, arithmetic right shift and logic right shift? Arithmetic left shift: add 0 at the end; logic left shift: add 0 at the end Arithmetic shift right: fill in the lowest bit at the left end; logic shift right: add 0 at the left end Why are there such differences? In addition, why are arithmetic left shift and logic left shift the same? In this case, why are there two kinds of instructions? Arithmetic shift right, is the left end of the highest fill
• 5. On the oscillation discontinuity of Higher Mathematics f（x）=sin（1/x）+1,x>0, sin（1/x）-1,x
• 6. If the sequence {CN} = {an} * {BN}, {an} is the arithmetic sequence and {BN} is the proportional sequence Find the sum SN of {CN}
• 7. If a set of data x1, X2 If the average of XN is 2 and the variance is 9, then the data are 2x1-3, 2x2-3 What are the average and variance of 2xn-3?
• 8. Does the angle between X, y, z axes in the coordinate system established by space vector have to be 90 degrees
• 9. It is known that: as shown in the figure, in RT △ ABC, ∠ C = 90 °, BC = 4, AC = 8, the point D is on the hypotenuse AB, make de ⊥ AC, DF ⊥ BC respectively, the perpendicular feet are e, f respectively, and get the quadrilateral decf, let de = x, DF = y. (1) use the algebraic formula containing y to express AE, and get AE=______ (2) find out the function relation between Y and X, and find out the value range of X; (3) let the area of quadrilateral decf be s, find out the maximum value of S
• 10. If the positions of rational numbers a, B and C on the number axis are shown in the figure below, where 0 is the origin. (1) find the value of the formula A / | a | + | B | / B + C / | C | + | ABC | / ABC --。 ---------------。 ----。 ---------。 ------------- a b 0 d
• 11. As shown in the figure, M is a point on the side ad of the parallelogram. If the area of the parallelogram ABCD is four square centimeters, what is the area of the triangle MBC
• 12. As shown in the figure, in trapezoidal ABCD, ad ∥ BC, diagonal AC and BD intersect vertically at O, Mn is the median line of trapezoidal ABCD, ∠ DBC = 30 °, verification: AC = Mn
• 13. As shown in the figure, in trapezoidal ABCD, ad ∥ BC, diagonal AC and BD intersect vertically at O, Mn is the median line of trapezoidal ABCD, ∠ DBC = 30 °, verification: AC = Mn
• 14. As shown in the figure, in trapezoidal ABCD, ad ∥ BC, diagonal AC and BD intersect vertically at O, Mn is the median line of trapezoidal ABCD, ∠ DBC = 30 °, verification: AC = Mn
• 15. The diagonals AC and BD of parallelogram ABCD intersect at point O, BF passes through point O, and intersect with AB and CD at points E and f respectively After modification: the diagonal lines AC and BD of parallelogram ABCD intersect at point O, EF passes through point O, and intersects with AB and CD at points E and f respectively
• 16. In trapezoidal ABCD, ad ‖ BC, ab = DC, AC, BD intersect with point O, and ∠ BOC = 60 ° Find the length of EF If e and F are the midpoint of OC and ab respectively, ad = 1 and BC = 2,
• 17. As shown in the figure, in ladder ABCD, ad is parallel to BC, ad is less than BC, ab = DC, AC, BD intersect at point O, the angle BOC = 60 degrees, e, F, G are the midpoint of Ao, Bo, DC respectively, prove that the triangle EFG is an equilateral triangle
• 18. As shown in the figure, in the isosceles ladder ABCD, ad ‖ DC, ab = DC, diagonal AC and BD intersect at point O, Bo = 6cm, e is a moving point on the edge of BC (point E does not coincide with B and C), EF ‖ BD intersects AC at point F, eg ‖ AC intersects BD at point g. during the movement of point E, try to guess whether the sum of the lengths of GH and EF changes? If so, explain your reason; if not, request its value
• 19. As shown in the figure, if the straight line EF passes through the intersection o of diagonal lines of parallelogram ABCD and intersects AB, CD at e and f respectively, the area of the shadow part is () A. 15B. 14C. 13D. 12
• 20. The figure below is a trapezoid, its area is unknown, the bottom 20 cm, there are two right angles, the other angle is 45 degrees