(1)如图1,若点D在AB上,将BD绕点D逆时针方向旋转150°得到线段ED,此时点E正好落在AC上,G是BC延长线上一点,连接DG交AC于点F,若DF=GF,AD=2,求EF的长;
(2)如图2,将BD绕点D逆时针方向旋转120°,连接AE、DC,点H是AE中点,连接CH交DE于点Q,连接DH,∠HDE=∠CDE.
①求证:DH=CQ;
②如图3,点M是BD中点,连接AM,将△ABM沿AB翻折至△ABN,当点N到直线AB的距离最大时,请直接写出的值.
同类型试题
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2