A. (1)将△PAB绕点B顺时针旋转90°到△P′CB的位置(如图1). ①设AB的长为a,PB的长为b(b<a),求△PAB旋转到△P′CB的过程中边PA所扫过区域(图1中阴影部分)的面积; ②若PA=2,PB=4,∠APB=135°,求PC的长. (2)如图2,若PA2+PC2=2PB2,请说明点P必在对角线AC上. |
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