【单选题】
正四棱锥的侧面是正三角形,则它的高与底面边长之比为 ()
①
img class=kfformula src=zzximg/20190809/1565327345365743.png data-latex=1:2/
②
img class=kfformula src=zzximg/20190809/1565327345233053.png data-latex=2:1/
③
img class=kfformula src=zzximg/20190809/1565327345190290.png data-latex=1:\sqrt {2}/
④
img class=kfformula src=zzximg/20190809/1565327345759526.png data-latex=\sqrt {2}:1/