弓形的弦ab长为L=8,弓高为H=2,求半径R? R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*R*H+H^2+L^2/4
2*R*H=H^2+L^2/4
R=H/2+L^2/(8*H)=2/2+8^2/(8*2) =5
2、半径为R=5,弓高为H=2,求弓形长L? L=2*(R^2-(R-H)^2)^0.5=2*(5^2-(5-2)^2)^0.5 =8
3、半径为R=5,弦长为L=8,求弓形高H?H=R-(R^2-(L/2)^2)^0.5=5-(5^2-(8/2)^2)^0.5 =2