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直角三角形中30度角所對的邊
直角三角形中30度角所對的邊
更新时间:2025-04-02 11:36:19

在直角三角形中,30°的角所對的邊等于斜邊的一半

BC=1/2AB

直角三角形中30度角所對的邊(直角三角形中30的角所對的在邊等于斜邊的一半)1

以AC為軸做△ABC軸對稱圖△ADC

∵∠BAC=∠DAC=30°

∴∠BAD=∠BAC ∠DAC=60°

∵∠BCA=∠DCA=90°

∴∠BCD=∠BCA ∠DCA=90° 90°=180°

BD為線段

∵∠CBA=∠CDA=∠BAD=60°

∴△BAD為等邊三角形

(等邊三角形,三條邊相等,三個角相等都是60度)

AB=AD=BD

∵BC=CD,AB=BD

∴BC=1/2AB

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