了解性质:如图1:已知四边形中,.垂足为,则有:;性质应用:(1)如图1,四边形是垂美四边形,若,,,则 ;
性质变式:(2)如图2,图3,P是矩形所在平面内任意一点,则有以下重要结论:.请以图3为例将重要结论证明出来.应用变式:(3)①如图4,在矩形中,O为对角线交点,P为中点,则;(写出证明过程)
②如图5,在中,,,D是内一点,且,,则的最小值是 .
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