Can I use this type of Logic when decideing whether or not to call?

[kingstalker]

Yesterday I had a opponet bet into me on the river when I had K-K(Two opponets on flop, one folded to the flop bet)I bet the flop and checked the turn which may have shown weakness and induced a bluff) on a
A-6-2-9-A board with two hearts on the flop, I made the call on the end becuase I figured the odds of him having a ace were about 11 to 1 against because of the two aces on board, I figured it was more likely he had a flush draw which missed and that is indeed what he had.Can I use the 11 to 1 or would I assume the standard he had a 1 in 3.5 chance of having a ace?