求一数学题的解析As in figure 2,the area of square ABCD is l69cm2,and the area ofthombus BCPQ is 156cm2.Then the area of the shadow part is ( )(A) 23cm2.(B) 33cm2.(C) 43cm2.(D) 53cm2.
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求一数学题的解析As in figure 2,the area of square ABCD is l69cm2,and the area ofthombus BCPQ is 156cm2.Then the area of the shadow part is ( )(A) 23cm2.(B) 33cm2.(C) 43cm2.(D) 53cm2.
求一数学题的解析
As in figure 2,the area of square ABCD is l69cm2,and the area of
thombus BCPQ is 156cm2.Then the area of the shadow part is ( )
(A) 23cm2.(B) 33cm2.(C) 43cm2.(D) 53cm2.
求一数学题的解析As in figure 2,the area of square ABCD is l69cm2,and the area ofthombus BCPQ is 156cm2.Then the area of the shadow part is ( )(A) 23cm2.(B) 33cm2.(C) 43cm2.(D) 53cm2.
设CD和PQ的交点为E(自己画一下啊),
正方形ABCD的面积是169cm²,
所以其边长BC为13cm,
而菱形BCPQ的面积是156cm²,
即 156=BC×CE,
求得CE=12cm,
由勾股定理,
CE²+PE²=PC²,
CE=12cm,PC=BC=13cm,解得PE=5cm
所以三角形PCE的面积为12×5/2=30cm²,
故梯形QEBC的面积为156-30=126cm²,
于是阴影部分的面积为:正方形ABCD的面积减去梯形QEBC的面积
169-126=43cm²