定义:两条对角线相等的凸四边形叫做等线四边形,两条对角线所夹锐角为的等线四边形叫做强等线四边形.
(1)【理解运用】
下列四边形中,一定是等线四边形的是________(只填序号);
①平行四边形;②矩形;③菱形;④正方形.
(2)【拓展提升】
如图,中,,分别以,为边向外作菱形和 菱形,且,连接,,.
①求证:四边形是强等线四边形;
②若,,,分别是,的中点,连接,直接写出的长.
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