Olympiad Notes: Understanding Geometrical Shapes | Science Olympiad for Class 5 PDF Download

Closed-Sided Figure

A closed shape is like a drawing where you begin and finish at the same spot, with no open ends. It's a complete shape with no gaps or loose ends.

Examples of closed-sided shapes

Open-Sided Figure

An open shape is like a drawing where the lines don't connect and don't start and finish at the same spot. It's like a shape with some parts left open or lines that don't meet.
Examples of open-sided shapes

Question for Olympiad Notes: Understanding Geometrical Shapes

Try yourself:Which of the following shapes is a not closed-sided figure?

• A.

  Triangle
• B.

  line
• C.

  Circle
• D.

  Pentagon

Explanation

The line is not a closed-sided figure. Closed-sided figures have connected sides that form a complete boundary.

• A triangle has three sides.
• A circle is also closed, with a continuous curved line.
• A pentagon has five sides.
• The line does not enclose any area and is open-ended.

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Polygon

A polygon is a closed figure with straight sides.

• A polygon needs at least three straight sides to make a closed shape.

Shapes

Shapes are how things look, like the outline or outer surface of an object.

• Everything we see has a shape, like squares, rectangles, and ovals in 2D, or rectangular prisms, cylinders, and spheres in 3D.

List of Shapes

A. Circle

• A circle is a round-shaped figure with no corners or edges.
• It is a closed, two-dimensional curved shape.
• The angles in a circle sum to 360 degrees.

B. Triangle

• A triangle is a closed, two-dimensional form with three straight sides in geometry.
• The sum of the angles of a triangle is 180 degrees.

C. Quadrilateral

• A quadrilateral is a two-dimensional shape with four sides.
• All of the following 2D shapes are quadrilaterals: square, rectangle, and so on.
• The sum of the angles of a quadrilateral is 360 degrees.

D. Pentagon

• A pentagon is a five-sided geometrical form with five angles.
• The sum of the angles of a pentagon is 540 degrees.

E. Hexagon

• A hexagon is a six-sided geometrical form with six angles.
• The sum of the angles of a hexagon is 720 degrees.

F. Heptagon

• A heptagon is a seven-sided geometrical form with seven angles.
• The sum of the angles of a heptagon is 900 degrees.

G. Octagon

• An octagon is an eight-sided geometrical form with eight angles.
• The sum of the angles of an octagon is 1080 degrees.

H. Nonagon

• A nonagon is a nine-sided geometrical form with nine angles.
• The sum of the angles of a nonagon is 1260 degrees.

I. Decagon

• A decagon is a ten-sided geometrical form with ten angles.
• The sum of the angles of a decagon is 1440 degrees.

Question for Olympiad Notes: Understanding Geometrical Shapes

Try yourself:

Which shape has a sum of angles equal to 1260 degrees?

• A.

  Hexagon
• B.

  Nonagon
• C.

  Heptagon
• D.

  Octagon

Explanation

- A hexagon has a sum of angles equal to 720 degrees.
- A nonagon has a sum of angles equal to 1260 degrees.
- A heptagon has a sum of angles equal to 900 degrees.
- An octagon has a sum of angles equal to 1080 degrees.

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