x=acosøcosβ,y=bcosøsinβ,z=csinø
x/a=cosøcosβ y/b=cosøsinβ z/c=sinø
所以(x/a)^2+(y/b)^2+(z/c)^2=(cosøcosβ)^2+(cosøsinβ)^2+(sinø)^2=cosø^2*(cosβ^2+sinβ^2)+sinø^2=cosø^2+sinø^2=1
即(x/a)^2+(y/b)^2+(z/c)^2＝1
希望我表达的够清楚～