创建解题讲解视频---**Extraction Content:**
**Question Information:**
* Question Number: 16
* Points: 7分
**Problem Description:**
图1、图2、图3均是6×6的正方形网格, 每个小正方形的顶点称为格点,点A,B,C均在格点上. 仅用无刻度直尺, 在给定网格中按要求作图(保留作图痕迹,不要求写做法).
**(1)** 如图1,已知 AC 经过点 B, 画出 AC 所在圆的圆心 O;
**(2)** 在图2 中找一格点 D,使∠ADB = ∠ACB (找出 一个符合条件的格点即可);
**(3)** 在图3 中,正方形网格中的圆经过格点 A,B.画出该圆的圆心 O.
**Diagram Descriptions:**
**图1 (Figure 1):**
* Type: Grid with points and a curve.
* Main Elements:
* Grid: A 6x6 square grid. The vertices of the small squares are grid points.
* Points: Points A, B, and C are marked on grid points.
* Point A is approximately 1 unit right and 4 units up from the bottom-left grid intersection.
* Point B is approximately 3 units right and 5 units up from the bottom-left grid intersection.
* Point C is approximately 5 units right and 4 units up from the bottom-left grid intersection.
* Curve: A curved line passes through points A, B, and C. The curve appears to be an arc of a circle.
* Label: "图1" is placed below the grid.
**图2 (Figure 2):**
* Type: Grid with points and line segments.
* Main Elements:
* Grid: A 6x6 square grid. The vertices of the small squares are grid points.
* Points: Points A, B, and C are marked on grid points.
* Point A is approximately 1 unit right and 4 units up from the bottom-left grid intersection.
* Point B is approximately 3 units right and 5 units up from the bottom-left grid intersection.
* Point C is approximately 5 units right and 1 unit up from the bottom-left grid intersection.
* Lines: Straight line segments connect A to B, B to C, and A to C, forming triangle ABC.
* Label: "图2" and "(第 16 题)" are placed below the grid.
**图3 (Figure 3):**
* Type: Grid with a circle and points.
* Main Elements:
* Grid: A 6x6 square grid. The vertices of the small squares are grid points.
* Points: Points A and B are marked on grid points on the circle.
* Point A is approximately 5 units right and 4 units up from the bottom-left grid intersection.
* Point B is approximately 1 unit right and 4 units up from the bottom-left grid intersection.
* Shape: A circle is drawn within the grid, passing through points A and B. The center of the circle appears to be on the horizontal line passing through A and B. The circle seems to be centered at approximately (3, 4) relative to the bottom-left grid intersection.
* Label: "图3" is placed below the grid.
**Other Text:**
* Line: "内线" (Inside Line) - Likely a boundary marker.
* Text labels below the problem: "题", "答", "要", "不" - Likely labels for different sections of an answer sheet (e.g., Problem, Answer, Required, Not allowed/applicable).