理解角度（10岁以上）
Understanding angles (age 10+)
认识一点处的角、一条直线上的角以及对顶角；利用这些性质求未知角。
Recognise angles where they meet at a point, are on a straight line, or are vertically opposite; find missing angles using these properties
学习证据 / Evidence
- 已知一点处的其他角，求该点处的缺失角（总角度为360°）。
- 利用一条直线上角的性质（角度之和为180°）求未知角。
- 识别对顶角，并利用对顶角相等的性质求未知角。
- Find a missing angle at a point given the other angles (total 360°)
- Use the straight-line property (angles sum to 180°) to find an unknown angle
- Identify vertically opposite angles and use the property that they are equal to find unknowns
评估问题 / Assessment
如果两条直线相交，{{name}}能告诉你哪对角相等（对顶角），并在你给它其中一个角时找出缺失的角吗？
If two straight lines cross each other, can {{name}} tell you which pairs of angles are equal (vertically opposite) — and find a missing angle if you give them one of the others?