解:圆心为O,则OA=OB=OC=OD=半径R,设腰长为x
(1)设上底长是2b,过C作直径的垂线,垂足是P,则x^2-(R-b)^2=R^2-b^2=CP^2
带入整理得b=R-x^2/(2R),所以
y=2R+2x+2b
=2R+2x+2R-x^2/R
=-x^2/R+2x+4R 定义域:0
解:圆心为O,则OA=OB=OC=OD=半径R,设腰长为x
(1)设上底长是2b,过C作直径的垂线,垂足是P,则x^2-(R-b)^2=R^2-b^2=CP^2
带入整理得b=R-x^2/(2R),所以
y=2R+2x+2b
=2R+2x+2R-x^2/R
=-x^2/R+2x+4R 定义域:0