解答:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/9358d109b3de9c82b8fef73d6f81800a18d843ec?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
解:(1)如图,∵在△ABC中,∠B=70°,∠C=30°,
∴∠BAC=180°-∠B-∠C=180°-70°-30°=80°,
∵AE平分∠BAC,
∴∠BAE=
∠BAC=
×80°=40°;
∵AD⊥BC,∠B=70°,
∴∠BAD=90°-∠B=90°-70°=20°,
∵∠BAE=40°,
∴∠DAE=∠BAE-∠BAD=40°-20°=20°;
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/241f95cad1c8a786632d728a6409c93d70cf502a?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
(2)如图,∵AE平分∠BAC,
∴∠BAE=
(180°-∠B-∠C),
∵AD⊥BC,
∴∠BAD=90°-∠B,
∴∠DAE=∠BAD-∠BAE=(90°-∠B)-
(180°-∠B-∠C)=
(∠C-∠B)=
α.