user4045: I just played chess on my mac and the computer (black) won. Here's the final board:

Why couldn't I, white, use my king (D4) to take the black queen (C5)?

user-1: Because the queen is protected by the bishop on A3. Therefore its checkmate.

4045: <p>I just played chess on my mac and the computer (black) won. Here's the final board:</p>

<p><img src="https://i.stack.imgur.com/bBwdr.jpg" alt="Final board"></p>

<p>Why couldn't I, white, use my king (D4) to take the black queen (C5)?</p>
 -1: <p>Because the queen is protected by the bishop on A3. Therefore its checkmate.</p>
