圆心角A=2弧度,所对的弦长L=2,这个扇形的面积S是多少?

　　弧半径为R,弧长为C.

　　R=(L/2)/SIN(A/2)

　　=(2/2)/SIN(2/2)

　　=1/SIN(1弧度)

　　C=A*R=2*(1/SIN(1弧度))=2/SIN(1弧度)

　　S=C*R/2=(2/SIN(1弧度))*(1/SIN(1弧度))/2=(1/SIN(1弧度))^2