郊县 | 人数/万 | 人均耕地面积/公顷 |
A | 20 | 0.15 |
B | 5 | 0.20 |
C | 10 | 0.18 |
求甲市郊县所有人口的人均耕地面积(精确到0.01公顷);
(2)先化简下式,再求值:,其中;
(3)如图,已知A,B,C,D是⊙O上的四点,延长DC,AB相交于点E,若BC=B
A.求证:△ADE是等腰三角形. |
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