Tangled is a major reason for Frozen's success. Tangled was a movie that people loved in theatres and loved on DVD, and Frozen is in the same Disney Princess vein. Frozen benefitted from and built on Tangled's success to make even more money. Think of it as The Little Mermaid opening doors for Beauty and the Beast to earn even more money.
Without Tangled, Frozen wouldn't have gone anywhere near $300M+.