1.选择题:设r为圆的半径,则弧长为3/4r的圆弧所对的圆心角为( ) A.135° B.135°/π C.145° D.145°/

问题描述:

1.选择题:设r为圆的半径,则弧长为3/4r的圆弧所对的圆心角为( ) A.135° B.135°/π C.145° D.145°/

3/4r/2πr *360°=135°/π
答案:B.135°/π