奥数 六年级比赛 几何直线形面积 燕尾定理.教员版word(国外英文资料).docVIP

奥数 六年级竞赛 几何直线形面积 燕尾定理.教师版word(国外英文资料) So the ratio of the shaded area to the blank area. Method 2: connect to CG, CH, AC, AC to BD, yes In the middle, according to the swallowtail theorem, so, so, In the same way, according to the dovetail theorem, So, so So the ratio of the shaded area to the blank area 9 cases as shown in figure, in the two area in a trapezoid respectively 10 and 12 of the triangle, trapezoid on the bottom is the bottom long known, so the rest of the area of the shaded part is ______. The bottom is a 2a, and then the lower base is 3a, the height of the trapezoid is the area of the trapezoid 45. So the shaded area is going to be In the middle, in the middle, in the middle. [analysis] connection. Because, therefore, According to the yantail theorem. In a triangle, its a right Angle, and we know, what is the area of the triangle (the shaded part)? [analysis] connection. The area of According to the yantail theorem, In the same way Lets say the area is 1, and the area is 1, so the area is 1, and the area is 4, so the area is 1, so the area is 1. The area of triangle ABC is 1 square centimeter, and BE2EC, F is the midpoint of the CD. [analysis] connection BF, according to dovetail theorem, and because F is the midpoint of CD, so, so, namely D is the midpoint of AB, (a), (a), (a) and (a), (a), So (square centimeter) As you can see, the line segment AB is perpendicular to BC, and we know that AD = EC = 4, DB = BE equal to 6, so what is the area of the shaded area? This graph is a symmetric graph, and the length of each side has been given, so lets take a look at the symmetry axis of this graph. As a helper line BO, the graph is about BO symmetry, The area of delta ADO is 2, the area of delta DBO is 3, and the area of the right triangle ABE is 8. Because the area of the shaded area is 4, So the area of the shaded area is The area of the figure, which is 1 square centimeter, is square centimeters. [analysis] because, in parallel, So,,, And because, again,