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Mid-Term Exam Review Project. Chapter 5. Quadrilaterals. Chapter 5: Break Down . 5-1: Properties of Parallelograms 5-2: Ways to Prove that Quadrilaterals are Parallelograms 5-3: Theorems Involving Parallelograms 5-4 : Special Quadrilaterals 5-5: Trapezoids. Chapter 5: Section 1.
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Mid-Term Exam Review Project Chapter 5 Quadrilaterals
Chapter 5: Break Down • 5-1: Properties of Parallelograms • 5-2: Ways to Prove that Quadrilaterals are Parallelograms • 5-3: Theorems Involving Parallelograms • 5-4 : Special Quadrilaterals • 5-5: Trapezoids
Chapter 5: Section 1 Properties of Parallelograms
Parallelograms A parallelogram is a quadrilateral with both pairs of opposite sides parallel. But there are more characteristics of parallelograms than just that…
These additional characteristics are applied in several theorems throughout the section.
Theorem 5-1 “Opposite sides of a parallelogram are congruent.”
This theorem states that the sides in a parallelogram that are opposite of each other are congruent. This means that in ABCD, side AB is congruent to side CD and side AC to side BD. A B D C
Theorem 5-2 “Opposite Angles of a parallelogram are congruent”
This theorem states that in a parallelogram, the opposite angles of a parallelogram are congruent.
Theorem 5-3 “Diagonals of a parallelogram bisect each other”
This theorem states that in any parallelogram the diagonals bisect each other.
Section 5-2 Ways to Prove that Quadrilaterals are Parallelograms
5 Ways to Prove that a Quadrilateral is a Parallelogram • Show that both pairs of opposite sides are parallel • Show that both pairs of opposite sides are congruent • Show that one pair of opposite sides are both congruent and parallel • Show that both pairs of opposite angles are congruent • Show that the diagonals bisect each other
Theorem 5-4 “If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram.”
Theorem 5-4 T S R Q This theorem states that if side TS is congruent to side QR and side QT is congruent to side SR, then the quadrilateral is a parallelogram.
Theorem 5-5 “If one pair of opposite sides of a quadrilateral are both congruent and parallel, then the quadrilateral is a parallelogram.”
Theorem 5-5 V L • Theorem 5-5 states that if side VL and side AD are both parallel and congruent, then the quadrilateral is a parallelogram. D A
Theorem 5-6 “If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram.”
Theorem 5-6 M I • This theorem states that if angle M is congruent to angle E, and angle I is congruent to angle K, then quadrilateral MIKE is a parallelogram. K E
Theorem 5-7 If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram.
Theorem 5-7 H D • This theorem states that if segment HA is congruent to segment AT, and segment MA is congruent to segment AD, that quadrilateral HDMT is a parallelogram. A M T
Chapter 5: Section 3 • Theorems Involving Parallel Lines
Theorem 5-8 • “If two lines are parallel, then all points on one line are equidistant from the other line.”
All of the points on a line are equidistant from points on the perpendicular bisector of a parallel line.
Theorem 5-9 • “If three parallel lines cut off congruent segments on one transversal, then they cut off congruent segments on every transversal.”
Theorem 5-10 • “A line that contains the midpoint of one side of a triangle and is parallel to another side passes through the midpoint of the third side.”
Theorem 5-11 • “The segment that joins the midpoints of two sides of a triangle.” 1) is parallel to the third side 2) is half the length of the third side
Section 5-4 Special Parallelograms
Special Parallelograms • There are four distinct special parallelograms that have unique characteristics. • These special parallelograms include: • Rectangles • Rhombi • Squares
Rectangles • A rectangle is a quadrilateral with four right angles. Every rectangle, therefore, is a parallelogram.
Why? • Every rectangle is a parallelogram because all angles in a rectangle are right, and all right angles are congruent. • If the both pairs of opposite angles in a quadrilateral are congruent, then the quadrilateral is a parallelogram.
Additionally: • If a rectangle is a parallelogram, then it retains all of the characteristics of a parallelogram. If this is true then name all congruencies in the following diagram. A S R D E
Solution: S A R D E
Rhombi • A rhombus is a quadrilateral with four congruent sides. Therefore, every rhombus is a parallelogram.
Why? • Every rhombus is a parallelogram because all four sides are congruent, and therefore both pairs of opposite sides are congruent.
Squares • A square is a quadrilateral with four right angles and four congruent sides. Therefore, every square is a rectangle, a rhombus, and a parallelogram.
Why? • A square is a rectangle a rhombus, and a parallelogram because all four sides are congruent and all four angles are right angles.
Theorems • Theorem’s 5-12 through 5-13 are very simple and self explanatory. They read as follows: • 5-12: The diagonals of a rectangle are congruent • 5-13: The diagonals of a rhombus are perpendicular. • 5-14: Each diagonal of a rhombus bisects two angles of the rhombus.
Theorem 5-12 S A • According to theorem 5-12, segment SE is congruent to segment DA R D E
Theorem 5-13 A • According to theorem 5-13, segment AD is congruent to segment CB. B C D
Theorem 5-14 A • According to theorem 5-14, segment AD bisects angle BAC and angle BCD, and segment BC bisects angle ABD and angle ACD. B C D
Theorem 5-15 “The Midpoint of the hypotenuse of a right triangle is equidistant from the three vertices.”
Theorem 5-15 A M B C According to this theorem, M is equidistant from points A, B, and C.
Theorem 5-16 If an angle of a parallelogram is a right angle, then the parallelogram is a rectangle.
Theorem 5-16 M A • In MATH, we know that angle H is a right angle. This means that all of the angles are right angles, and that MATH is a rectangle. (According to Theorem 5-16) H T
Theorem 5-17 If two consecutive sides of a parallelogram are congruent, then the parallelogram is a rhombus.
Theorem 5-17 A • In MATH, if we know that segment MA is congruent to segment AT, then we know that MATH is a rhombus, because segment MA is congruent to segment TH and segment AT is congruent to segment MH. Therefore, all sides are congruent to each other. M T H
Section 5-5 Trapezoids
Trapezoid • A trapezoid is defined as a quadrilateral with exactly one pair of parallel sides.