1.已知CD为RT△ABC斜边上的高,且S△ADC的平方=S△ABC*S△BCD,求sinA的值.2.设α为锐角,满足tanα=3,求(2cosα-sinα)/(4cosα+5sinα)的值.3.RT△ABC的三边长为3,4,5,P为其内部一点,求使PA+PB+PC的值最小的值.原题
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![1.已知CD为RT△ABC斜边上的高,且S△ADC的平方=S△ABC*S△BCD,求sinA的值.2.设α为锐角,满足tanα=3,求(2cosα-sinα)/(4cosα+5sinα)的值.3.RT△ABC的三边长为3,4,5,P为其内部一点,求使PA+PB+PC的值最小的值.原题](/uploads/image/z/1676311-7-1.jpg?t=1.%E5%B7%B2%E7%9F%A5CD%E4%B8%BART%E2%96%B3ABC%E6%96%9C%E8%BE%B9%E4%B8%8A%E7%9A%84%E9%AB%98%2C%E4%B8%94S%E2%96%B3ADC%E7%9A%84%E5%B9%B3%E6%96%B9%3DS%E2%96%B3ABC%2AS%E2%96%B3BCD%2C%E6%B1%82sinA%E7%9A%84%E5%80%BC.2.%E8%AE%BE%CE%B1%E4%B8%BA%E9%94%90%E8%A7%92%2C%E6%BB%A1%E8%B6%B3tan%CE%B1%3D3%2C%E6%B1%82%282cos%CE%B1-sin%CE%B1%29%2F%284cos%CE%B1%2B5sin%CE%B1%29%E7%9A%84%E5%80%BC.3.RT%E2%96%B3ABC%E7%9A%84%E4%B8%89%E8%BE%B9%E9%95%BF%E4%B8%BA3%2C4%2C5%2CP%E4%B8%BA%E5%85%B6%E5%86%85%E9%83%A8%E4%B8%80%E7%82%B9%2C%E6%B1%82%E4%BD%BFPA%2BPB%2BPC%E7%9A%84%E5%80%BC%E6%9C%80%E5%B0%8F%E7%9A%84%E5%80%BC.%E5%8E%9F%E9%A2%98)
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