Question

如图,在Rt△ABC中,∠C=90°,sinB=5/13,点D在BC上，且∠ADC=45°，AC=5，求∠BAD的正弦值

回答好给奖励啊

Answer 1

求sinBAD
sinBAC=12/13 cosBAC=5/13 sinDAC=cosDAC=二分之根2
sinBAD=sin(BAC-DAC)=sinBACcosDAC-cosBACsinDAC=26分之7根2