22和23题.谢谢~
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/02 20:06:51
22和23题.谢谢~
![22和23题.谢谢~](/uploads/image/z/3869162-26-2.jpg?t=22%E5%92%8C23%E9%A2%98.%E8%B0%A2%E8%B0%A2%EF%BD%9E%26nbsp%3B)
22、先求∠BAC=180°-∠B-∠BCA=180°-36°-110°=34°
∵AE平分∠BAC,
∴∠ECA=1/2·∠BAC=1/2·34°=17°
∵∠BCA=∠D+∠CAD
∴∠CAD=∠BCA-∠D=110°-90°=20°
∴∠DAE=∠ECA+∠CAD=17°+20°=37°
23、(1)S△ABC=1/2·AC·BC=1/2·6×8=24
(2)由1/2·AC·BC=1/2·AB·CD得
CD=AC·BC/AB=6×8/10=4.8
(3)S△ABE=1/2·S△ABC=1/2×24=12.
∵AE平分∠BAC,
∴∠ECA=1/2·∠BAC=1/2·34°=17°
∵∠BCA=∠D+∠CAD
∴∠CAD=∠BCA-∠D=110°-90°=20°
∴∠DAE=∠ECA+∠CAD=17°+20°=37°
23、(1)S△ABC=1/2·AC·BC=1/2·6×8=24
(2)由1/2·AC·BC=1/2·AB·CD得
CD=AC·BC/AB=6×8/10=4.8
(3)S△ABE=1/2·S△ABC=1/2×24=12.