圆台的内切球的半径为R,而圆台的全面积和球面积之比是21/8求圆台上下底面半径R1,R2?

圆台纵截面先画出 派=PI得两腰为=R1+R2台高2R有(R2-R1)^2+(2R)^2=(R1+R2)^2 ←(得R^2=R1*R2)圆台的全面积=PI(R1+R2)^2球面积=4PI*R^2圆台的全面积和球面积之比是21/8所以2(R1+R2)^2=21R^2 ←解上述两条方程可得有点...