Points: A point is
a dot that is so small that its height and width are actually zero!
Lines: A line is
as wide as a point, infinitely thin, having an infinite number of points, (in a
straight row), extending forever in both the directions.
Angles: An angle (∠)
is made up of a vertex (a point), two arms (rays), and an arc. They are
arranged so that the endpoint of the arms are the same as the vertex, and the
arc runs from one arm to another. The size of an angle depends on how big the
arms are opened, and they are measured in degrees.
Solids: Solids are
shapes that you can actually touch. They have three dimensions, which means
that the have length, width and height.
Measurements: When
measuring length, simply put get a ruler and place the '0' on the endpoint of
the segment you wish to measure. Then move the ruler so that the edge of the
ruler fits the line exactly. Read the marking on the ruler on the other
endpoint. That is the length of the ruler.
Parallel lines: Parallel
lines are straight lines that never intersect, which means that they never
cross. Notice that when we look at parallel parts of shapes there is no place
where they intersect even if we extend the lines.
Symmetry: A figure
is considered to have reflectional symmetry when a half of the figure coincides
with the other half when folded in half (an easier way to say it would be
saying it looks exactly the same on both sides).
Transformation: Transformation
is when we change the size, orientation, and/or position of a shape. Note that
transformation is usually done on graph paper to avoid excessive meaurements
and ensure accuracy.
Coordinates: Coordinates
are very useful in daily lives. Without them, the longitude and latitudes, and
grid references would be lost, making it impossible to navigate. Many of the
things you learn in computer literacy lessons, such as image editing, would be
harder.
Plane shapes: Any shape that can be drawn in the plane is
called a plane figure.
Ex:
1) Triangle:
A triangle is a shape with three sides. It can be classified according to its
sides or angles, with three kinds each. Here they are:
-
Equilateral triangles, which are also equiangular
triangles, have three sides equal and three angles equal. Their angles are
always 60°.
-
Isosceles triangles are triangles in
which two of the sides are equal. The non-included angles of the sides are also
equal.
-
Scalene triangles have no equivalence in
any way.
-
Right triangles are triangles with a
right angle. The longest side of such triangles is called a hypotenuse.
-
Obtuse triangles are triangles with an
obtuse angle.
-
Acute triangles are triangles with no
right or obtuse angle.
2) Quadrilaterals: A quadrilateral is a shape with four sides.
You will spend a lot of time with these. They can be classified into
many different categories:
- Parallelograms are shapes where
opposite sides and angles are equal. The opposite sides are parallel, hence the
name.
-Rectangles are parallelograms
where the angles are all 90°. Its width or breadth refers to the shorter sides,
while its length refers to its longer ones.
- Rhombuses
are parallelograms where all the sides are equal, and opposite angles are
equal.
-Squares are parallelograms that
are both rectangles and rhombuses, i.e. all angles are right and all sides are
equal.
-Trapeziums, called trapezoids in
American English, have two opposite sides that are parallel. The parallel sides
are sometimes called the upper and lower bases.
- Right-angles trapeziums are
trapeziums with a right angle.
-Isosceles trapeziums are
trapeziums where the laterals sides are equal but not parallel.
-Scalene trapeziums are
trapeziums that fall into neither category.
Other:
·
Pentagons have five sides.
·
Hexagons have six sides.
·
Heptagons or septagons have seven sides.
·
Octagons have eight sides.
·
Nonagons have nine sides.
·
Decagons have ten sides.
