Plane Shapes

When a shape is flat or two dimensional and it is closed, it is called Plane shape. They have width and breath but there is no thickness whatsoever, the major reason why it is two dimensional. Examples are square, rectangle, triangle, trapezium, rhombus and circle etc. A Plane is a flat surface, such as the top of a table, playing field, wall and ceiling etc

Classification of plane shapes..

Regular plane shapes are shapes with definite length and breadth; they have clear and straight edges. E.g. square, rectangle etc.

Irregular plane shapes are shapes with indefinite length and breadth, their edges are crooked. E.g the shape of leaves.

Identifying plane shapes

Rectangle

A Rectangle is a four sided-polygon, having all the internal angles equal to 90 degrees. The two sides at each corner, meet at right angles. The opposite sides of the rectangle are equal in length which makes it different from a square.

Properties of Rectangle

(i) Opposite sides are equal and parallel;

(ii) it has equal angle, each angle is 90⁰;

(iii) the diagonal lines are equal and bisect each other;

(iv) it has two lines of symmetry

Triangle

Classification according to their sides or lengths

Equilateral Triangle: A triangle with equal sides and equal angles.

Properties of Equilateral triangle

• All sides are equal
• It has three lines of symmetry
• All angles are equal; each 60⁰

Isosceles Triangle: A triangle with two equal sides and equal base angles.

Properties of Isosceles triangle

1. Two sides are equal.
2. Base angles are equal.
3. It has one line of symmetry.

Scalene Triangle: A triangle that has no equal sides

Properties of scalene triangle

1. None of the three sides are equal.
2. None of the three angles are equal.
3. It has no line of symmetry.

Parallelogram: Is a four sided plane shape.

Properties of parallelogram

1. Opposite sides are equal.
2. Opposite sides are parallel.
3. Opposite angles are equal.

Trapezium: is a four sided plane shape

Properties of Trapezium

1. It one pair of parallel sides.
2. The parallel sides are not equal.

Circle

A circle is a geometrical shape that is made by drawing a curve that always has the same distance from the point that we refer to as the center.

Parts of circle

• Circumference: Is the distance round the circle.
• Arc: Is a portion of a circumference
• Diameter: Is the line that divides the circle into two equal parts and passes through the centre.
• Radius: Is the line from the centre of the circle to the circumference.

Rex Ogundele

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