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Inside, outside and on the boundary
Textbook Part 4, pp. 26–27
GoalTell the boundary, the inside region and the outside of a shape apart.
New words
boundary (border) · chegararegion (inside) · sohaoutside · tashqaridashared region · umumiy soha
Explanation
A shape’s boundary is the closed line around it. Its region is the inside. A point can lie on the boundary, inside or outside the shape. When two circles overlap they have a shared region.
Worked examples
On the map of Uzbekistan the border is a line and the land inside is shown in colour.
An envelope has 35 triangles and 22 fewer squares: 35 − 22 = 13 squares; 48 shapes in all.
Class activity
A big rope circle on the floor. The teacher calls “stand on the boundary”, “go inside”, “go outside”. With two circles: “stand in the shared region”.
Practice
1
What is the inside of a shape called?
The region
2
35 triangles and 22 fewer squares. How many shapes?
48
3
A point in the shared region of two circles is inside how many circles?
2
4
52 + 13 − 20 = ?
45