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下课后,老师布置了一道课外练习:已知梯形ABCD的面积是90平方厘米,下底AB=12厘米,高9厘米,三角形DOC的面积为10平方厘米,阴影部分ABO的面积是多少平方厘米?丽丽回家后左思右想也没有解答出来,于是,去请教小博士。小博士看了看题目,分析说:“已知ABO的底AB=12厘米,要求它的面积必须还要知道它的高。题目告诉我们梯形高9厘米,如果用梯形的高9厘米减去三角形DOC底边上的高,就可得到三角形AOB底边AB上的高,
After class, the teacher arranged an extracurricular exercise: it is known that the area of the trapezoidal ABCD is 90 square centimeters, the bottom AB = 12 centimeters, the height 9 centimeters, the area of the triangular DOC 10 square centimeters, and the area of the shadow ABO the area is square centimeters After Lily left home thinking left and right did not answer it, so go to consult a small doctor. Little Doctor looked at the topic, the analysis said: ”ABO known AB = 12 cm, requiring its area must also know its high. " The title tells us trapezoid 9 cm high, if the trapezoidal 9 cm high minus Go to the top of the triangle DOC bottom high, you can get triangle AOB Bottom AB high,