弓形的弦AB=4根号3,高CD=2cm,求弓形ACB的弧长和面积
问题描述：
弓形的弦AB=4根号3,高CD=2cm,求弓形ACB的弧长和面积
答
设圆心O,半径为R
则 (R-2)² +(2√3)² = R²
解得R=4
易知∠AOB=2π/3
∴弧长=2π/3 ×4 = 8π/3
S =1/2 ×4√3 ×2 = 4√3
S = 1/2 × 8π/3 ×4 = 16π/3
S = 16π/3 - 4√3