NUMERICAL LITERACY 2D & 3D 2D SHAPES A 2D geometric model is a geometric model of an object as two-dimensional figure. Something with two dimensions, e.g. height and width.
There are lots of 2D shapes. For example: SQUARE CIRCLE TRIANGLE TRAPEZIOD
RECTANGLE RIGHTANGLED TRIANGLE PARALLELOGRA M DECAGON
HEXAGON DODECAGO N MORE ABOUT 2D SHAPES.
TRIANGLE (2D SHAPES) A three-sided polygon. The sum of the angles of a triangle is 180 degrees. Equilateral Triangle or Equiangular Triangle.
- A triangle having all three sides of equal length. The angles of an equilateral triangle all measure 60 degrees. Isosceles Triangle - A triangle having two sides of equal length.
Scalene Triangle - A triangle having three sides of different lengths. Acute Triangle - A triangle having three acute angles
Obtuse Triangle - A triangle having an obtuse angle. One of the angles of the triangle measures more than 90 degrees.
Right Triangle - A triangle having a right angle. One of the angles of the triangle measures 90 degrees. The side opposite the right angle is called the hypotenuse. The two sides that form the right angle are called the legs. A right triangle has the special property that the sum of the squares of the lengths of the legs equals the square of
the length of the hypotenuse. This is known as the Pythagorean Theorem. SQUARE A four-sided polygon having equallength sides meeting at right angles. The sum of the angles of a square is 360
degrees. PARALLELOGRAM A four-sided polygon with two pairs of parallel sides. The sum of the angles of a parallelogram is 360 degrees. RHOMBUS
A four-sided polygon having all four sides of equal length. The sum of the angles of a rhombus is 360 degrees. TRAPEZOID A four-sided polygon having exactly one
pair of parallel sides. The two sides that are parallel are called the bases of the trapezoid. The sum of the angles of a trapezoid is 360 degrees. 3D SHAPES We live in a 3D world. Every object you
can see and touch has 3 dimensions that can be measured ie length, width, and height. There are lots of 3D shapes. For example:
SPHERE CYLINDER PYRAMID CONE PRISM
CUBE MORE ABOUT 3D SHAPES.. CUBOID Have 6 flat faces
Faces are all rectangles (square or oblong) Have 12 straight edges and 8 corners. SPHERE
No flat faces. No straight edges. Just one curved face
CUBE 6 flat square faces 12 straight edges
8 corners. CONE
It It It It has a flat base has one curved side has a curved surface is not a polyhedron.
CYLINDER It has a flat base and a flat top
The base is the same as the top, and also the crosssections It has one curved side Because it has a curved surface, it is not a polyhedron PRISM
A prism has the same cross-section all along its length A prism is officially a polyhedron, which means all sides should be flat. No
curved sides. The cross section is a polygon (a straight-edged figure). If the cross section was a circle then it would be a cylinder, not a prism. Square Prism: Cube: Cross-Section:
Cross-Section: (yes, a cube is a prism, because it is a square all along its length) Triangular Prism: Pentagonal Prism:
Cross-Section: Cross-Section: PYRAMID A pyramid is a polyhedron for which the
base is a polygon and all lateral faces are triangles. A pyramid is a geometric shape formed by connecting a polygonal face with a single point (the apex), thus creating n triangular faces (for a polygon of n vertices).