1. Introduction to congruent angles
Congruent Triangles
Introduction to congruent angles

2. Polygon
a closed plane figure formed by three or more segments that do not cross

3. having the same size or angle measure.
Congruent
having the same size or angle measure.
The symbol for congruent is So, the symbol, stands for “is congruent to.”

4. polygons with the same size AND shape.
Congruent Polygons
polygons with the same size AND shape. C A B F G E

5. parts of polygons that are matching and congruent.
Corresponding Parts
parts of polygons that are matching and congruent. C A B F G E

6. Need to Know!
**When stating congruent sides, the order that the segments are written in is very important, because it will identify direction.

7. Polygons and Quadrilaterals
What are the differences?

8. Name some quadrilaterals?
a FOUR sided polygon.
Name some quadrilaterals?
Square
Rectangle
Rhombus/ Diamond
Parallelogram
Trapezoid

9. What famous building houses the various armed forces? The Pentagon
a FIVE sided polygon.
What famous building houses the various armed forces?
The Pentagon

10. Hexagon
a SIX sided polygon.

11. Name a common object that has this shape. stop sign
Octagon
an EIGHT sided polygon.
Name a common object that has this shape.
stop sign

12. Decagon
a TEN sided polygon.

13. a polygon with ALL sides congruent and ALL angles congruent.
Regular Polygon
a polygon with ALL sides congruent and ALL angles congruent.
Name a regular polygon that is:
a triangle –
a quadrilateral –
Equilateral Triangle
Square

14. Parallel Lines
two lines that lie in the same plane (a flat surface) and DO NOT intersect

15. quadrilateral with exactly one pair of parallel sides
Trapezoid
quadrilateral with exactly one pair of parallel sides

16. quadrilateral with both pairs of opposite sides parallel
Parallelogram
quadrilateral with both pairs of opposite sides parallel

17. a parallelogram with 4 right angles
Rectangle
a parallelogram with 4 right angles

18. a parallelogram with 4 congruent sides
Rhombus
a parallelogram with 4 congruent sides

19. a parallelogram with 4 right angles and 4 congruent sides
Square
a parallelogram with 4 right angles and 4 congruent sides
What other names can a square have?
quadrilateral
parallelogram
rectangle
rhombus

20. Can a rectangle be a square?
Yes, but not always.
When?
Only if all 4 sides are also congruent.

21. Can a rhombus be a square?
Yes, but not always
When?
if all 4 angles are right angles.

22. Can a trapezoid be a rectangle?NO
Why?
Trapezoid can have only 1 set of parallel sides. Rectangle has 2.

23. Is a rectangle always a parallelogram?
Yes, by its definition.
a parallelogram with 4 right angles

24. Is a square always a rectangle?
Yes, ALWAYS!
It fits the definition of a rectangle because a square is a parallelogram, and has 4 right angles.

25. Is a rectangle always a square?NO
Only if the rectangle also has 4 congruent sides.

26. Diagonal
the segment that connects two corners of a polygon, but does not make a side of the polygon.
diagonals connect the inside of a polygon

27. Circles
Almost there…

28. a circle is named by its center
the set of points in a plane that are all the same distance from a given point, called the center.
a circle is named by its center

29. a segment from the center of a circle to a point on the circle.
Radius
a segment from the center of a circle to a point on the circle.
The plural form of radius is radii.

30. Diameter
a segment that passes through the center of a circle and has both endpoints on the circle.

31. a segment that has both endpoints on the circle.
Chord
a segment that has both endpoints on the circle.

32. an angle with its vertex at the center of a circle.
Central Angle
an angle with its vertex at the center of a circle.

33. a part of a circle (along the outside of the circle)
Arc
a part of a circle (along the outside of the circle)
named using just 2 letters

34. Semicircle
a half of a circle.
named using 3 letters
Why 3 letters?

35. a geometric tool used to draw circles and arcs.
Compass
a geometric tool used to draw circles and arcs.

36. a polygon whose sides are chords of a circle.
Inscribed Polygon
a polygon whose sides are chords of a circle.

37. A chord is always a diameter.
True or False?
FALSE!
not always, a chord IS a diameter, IF, it also passes through the center of the circle

38. A diameter is always chord.
True or False?
TRUE!
by definition, a diameter has two endpoints on the circle.

39. A diameter is equal, in length, to two radii.
True or False?
TRUE!
diameter is equal to the radius times 2.

40. only 1 part of a radius touches the circle, not two endpoints.
A radius can be a chord.
True or False?
FALSE!
only 1 part of a radius touches the circle, not two endpoints.

41. Identify! B F A C D E G