✔ 最佳答案
圖片參考:
https://s.yimg.com/rk/AD06198854/o/935984392.png
1.AB=AC的ΔABC中,D在AC上,BD=BC,E在AB上,AD=DE=EB,∠EDB=?
如左圖所示ΔBCD: 2y + (y-x) = 180 => y = (180 + x)/3
ΔABD: y = 外角 = x + z => z = y - x = (180 + x)/3 - x= (180 - 2x)/3= 2x (ΔBED: z = 外角)=> x = 180/8 = 22.5° = answer=> y = (180 + 22.5)/3 = 67.5°=> z = (180 - 2*22.5)/3 = 45°
2.ΔABC: ∠A=36°, ∠ACB=72°, BD平分∠ABC交AC於D, CE垂直BD交AB於E, 則共有多少等腰Δ?
如左圖所示:
等腰Δ = ΔABC(36°,72°,72°), ΔBCE(72°,54°,54°) = 2個
2015-04-04 05:22:36 補充:
第2題改為如右圖所示: