怒り and 驚き: emotions and visible reactions
Distinguish anger from surprise, using context to decide whether a surprise is welcome or unwelcome.
What anger concerns
怒り, read いかり, is the noun for anger. 不公平な扱いに怒りを感じました。 means that someone felt anger at unfair treatment.
怒りを抑えました。 says that the person held their anger in check. Do not expand this into anger having been absent from the start or having disappeared completely.
Encountering something unexpected
驚き, read おどろき, is surprise at something unexpected. 突然の知らせに驚きを隠せませんでした。 says that someone could not hide their surprise at sudden news.
驚きを隠せませんでした negates the ability to conceal the emotion. It does not negate being surprised, so check the scope of the negative.
What kind of surprise?
うれしい驚き is a pleasant surprise. The noun 驚き alone does not determine whether the event is good or bad.
怒りと驚きが入り交じっていました。 describes anger and surprise being mixed together. Translating only one of the emotions loses this combined state.
Does 驚きを隠せませんでした mean that the person was not surprised?
Show the answer and why
No. It means that the person could not hide their surprise. The negative concerns concealment, not the presence of surprise.