Introduction to congruent angles Congruent Triangles Introduction to congruent angles

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

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.”

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

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

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

Polygons and Quadrilaterals What are the differences?

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

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

Hexagon a SIX sided polygon.

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

Decagon a TEN sided polygon.

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

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

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

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

a parallelogram with 4 right angles Rectangle a parallelogram with 4 right angles

a parallelogram with 4 congruent sides Rhombus a parallelogram with 4 congruent sides

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

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

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

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

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

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.

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

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

Circles Almost there…

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

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.

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

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

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

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

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

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

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

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

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

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

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.

Identify! B F A C D E G