Question: Princess Frederica Dorothea "Louise" Philippine of Prussia, was a member of the House of Hohenzollern, and was a niece of which King of Prussia from 1740 until 1786, the longest reign of any Hohenzollern king?
Sentence (from "Princess Louise of Prussia (1770–1836)"): She was a niece of Frederick the Great, being the second daughter and third child of Prince Augustus Ferdinand of Prussia by his wife Margravine Elisabeth Louise of Brandenburg-Schwedt.
Relevant evidence: Yes