弧长等于直径的圆弧所对的圆周角为A .360°/π B.180°/π C.90°/π D.45°/π

弧长等于直径的圆弧所对的圆周角为A .360°/π B.180°/π C.90°/π D.45°/π
弧长等于直径的圆弧所对的圆周角为
A .360°/π B.180°/π C.90°/π D.45°/π

弧长等于直径的圆弧所对的圆周角为A .360°/π B.180°/π C.90°/π D.45°/π
B 设圆的半径是r,弧长就是2r,弧长所对的圆心角是A=2r/r=2 所对的圆周角是1（弧度）=180°/π

B 设圆的半径是r 直径就是2r 所以弧长就是2r 再用公式算结果