1. Notice, since polygons are Circles are not polygons.
Polygon: a closed figure formed by three or more line segments.
Notice, since polygons are
Circles are not polygons.
Hexagon
Quadrilateral
Triangle
Pentagon

2. Triangle: a polygon with three sides
Classified by sides
and angles

3. Congruent sides have the same length
Congruent sides have the same length. You can classify a triangle by the number of congruent sides it has.

4. Scalene triangle:
no congruent sides.

5. indicate congruent sides
Isosceles triangle:
at least two congruent sides.
Tick marks are used to
indicate congruent sides

6. All equilateral triangles are also isosceles triangles.
three congruent sides.
All equilateral triangles are
also isosceles triangles.

7. You can also classify a triangle by its angle
measures.

8. A square indicates the 90° angle in the right triangle.
one right angle
A square indicates the 90°
angle in the right triangle.

9. Acute triangle:
three acute angles (angles of less than 90°)

10. Obtuse triangle:
One obtuse angle
(angle greater than 90°)

11. Quadrilateral: a polygon with four sides
Parallelogram:
a quadrilateral with both pairs of opposite sides parallel.

12. Rectangle:
a parallelogram with four right angles
Square: a rectangle with four congruent sides

13. What is the area of this rectangle?

14. Length x Width or Base x Height

15. So how big is this rectangle?
Correct
48 square units
So how big is this rectangle?

16. A parallelogram
is formed which
has the same area
as the rectangle.
If, with the help of our 16th President, we chop a piece off the rectangle…
Then move
it to the
other side…

17. Always look for the 90° square.
And since it has
the same area,
we can use the
same formula.
base x height
Always look for the 90° square.

18. Don’t worry about
the length of the
sides. That is
called “slant
height.”

19. Sometimes you
will see the base
and height
connected
like this.

20. b x h 6 x 5 15 30 units units one-half base times height.
then the area of a triangle is…
If the area of a rectangle is b x h,
and a triangle is half a rectangle,

21. Does that only work with right triangles?NO

22. move it to form a rectangle. Copy this scalene triangle,
rotate it 180 degrees,
chop it at the vertex,
move it to form a rectangle.
Copy this scalene triangle,

23. Area = ½ bh 8m
10m
Area = (½)(10)(8) = 40m2

24. Trapezoid is related to trapeze. a circus elephant stands on,
but this polygon’s name
This may look like the stool
comes from the top of the circus.

25. The height is found between them. Trapezoids have one pair
base one
base two
The height is found between them.
Trapezoids have one pair
of parallel lines called bases.

26. the average of the bases
b1 + b2 2
Area = h
the average
of the bases
x the
height