如图，在△ABC中，AB=AC=10，点D是边BC上一动点（不与B、C重合），∠ADE=∠B=α，DE交AC于点E，且cosα=$\frac{4}{5}$，则线段CE的最大值为____ ．

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                                                                                                       戎昱
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                                                                                    黄莺久住浑相识，欲别频啼四五声。