Do little or nothing. Let your teammate vent. It may be difficult to sit still and take abuse from an angry person, but doing so will allow her to vent some pent-up anger. This will only increase her anger. Propose a remedy, if you have one.
Anger often goes hand in hand with powerlessness.
But if you ask an angry person to tell you what she wants you to do or say, you give her power. And that will often reduce her anger. Try to agree on a solution. Then, commit to taking the necessary actions. If you're not sure you can comply with the proposed remedy, ask for some time to consider and investigate.