请教1OG题

11. In ΔPQR, if PQ = x + 2, and PR = y, which of the three angles of ΔPRQ has the greatest
degree measure?
(1) y = x + 3
(2) x = 2

答案是A   我想问即使ＰＱ＝Ｘ＋２　　ＰＲ＝Ｙ＝Ｘ＋３　那还有第三条边不知道啊？　怎么就能判断哪条边哪个脚最大了？

先谢谢了