角的求和规则
Angle Sum Rules
知道一个点周围所有角的和为360°（一整圈），一条直线上的角的和为180°，对顶角相等；并利用这些知识求出未知角的度数。
Know that angles at a point sum to 360° (one whole turn), angles on a straight line sum to 180°, and vertically opposite angles are equal; use these facts to find missing angles
学习证据 / Evidence
- 说明一条直线上的两个角的度数相加等于180°
- 解释四个直角围成一个点，度数总共为360°
- 指出270°是三个直角的度数
- State that two angles on a straight line add to 180°
- Explain that four right angles at a point make 360°
- Identify 270° as three right angles
评估问题 / Assessment
如果三个角相交于一点，其中两个角分别是120°和95°，已知所有相交于一点的角的和是360°，{{name}}能算出第三个角吗？
If three angles meet at a point and two of them are 120° and 95°, can {{name}} work out the third angle — knowing all the angles at a point add up to 360°?