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一、问题的引出如图1,梯形ABCD中,AD//BC,AC和BD相交于点O,AD:BC=1:3,则S△ADO:S梯形ABCD:——.
First, the problem leads to Figure 1, trapezoidal ABCD, AD / / BC, AC and BD intersect at the point O, AD: BC = 1:3, then S△ ADO: S ladder ABCD: -.