Answer: 1) they believed that Hitler is someone they can negotiate with, i.e. that he will keep his word or the treaties he signed, 2) France was afraid of German expansionism and at the same time there was quite powerful French extreme-right (fascist) sympathizing with Hitler, 3) British policy of appeasement (conservative party which also partly sympathized with him), 4) they believed that satisfying Hitlers will resolve the tension in Europe, 5) they believed they could take advantage of him in their favour.
Explanation: Hitler´s political style was totally outside the box, absolutely unprecedented so his actions and strategies were totally unpredictible event though all that Hitler had described in his book "Mein Kampf".
