3-D shapes (II)
The faces of 3-D shapes: flat and curved faces, bases and lateral faces; a prism has two matching bases and rectangular side faces; a pyramid has one base and triangular side faces; and naming prisms and pyramids by the shape of the base, such as a pentagonal prism.
Key words
| Chinese | English |
|---|---|
| 面 | face |
| 曲面 | curved surface |
| 底 | base |
| 側面 | lateral face |
| 三角柱 | triangular prism |
| 四角錐 | square-based (quadrilateral) pyramid |
| 五角柱 | pentagonal prism |
The 4 short lessons and the chapter test
Lessons are in Chinese for now.
- 底、側面和曲面
- 角柱和角錐的名稱
- 看底命名
- 重溫
- 章節測驗 (chapter test)
Sample questions (in Chinese)
Question 1這個立體圖形叫甚麼名稱？
- 四角錐
- 三角柱
- 五角柱
- 四角柱
Answer and explanation
答案：D．四角柱
為甚麼？它上下兩個底一樣，側面是長方形或正方形，是角柱。它的底是四邊形，有 4 條邊，所以叫四角柱。
Question 2下面哪一個是三角錐？
Answer and explanation
答案：B
為甚麼？三角錐的底是三角形，只有一個底，側面是三角形，在尖頂相交。
Question 3這是六角柱。它有多少個面？
有 個面。
Answer and explanation
答案：有 8 個面。
為甚麼？六角柱的底是六邊形，有 6 條邊，所以有 6 個側面。角柱有 2 個底，共有 2 + 6 = 8 個面。
Question 4把這個四角錐的底沾上顏料，印在紙上。會印出哪一個圖形？
Answer and explanation
答案：C
為甚麼？印出來的是底的形狀。四角錐的底是四邊形。
Based on learning unit 2S1 of the Education Bureau’s Primary Mathematics Curriculum (2017).