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