Geometry - Properties of Parallelograms

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Questions and Answers

A quadrilateral with both pairs of opposite sides parallel is called a ______.

parallelogram

In a parallelogram, all four angles are congruent.

False (B)

Match the following properties with their corresponding quadrilateral type:

Opposite sides are congruent = Parallelogram All angles are right angles = Rectangle All sides are congruent = Rhombus All sides are congruent and all angles are right angles = Square

Which of the following is NOT a property of a parallelogram?

<p>All angles are right angles (A)</p> Signup and view all the answers

If two opposite angles of a quadrilateral are congruent, is it necessarily a parallelogram? Explain your answer.

<p>No, it is not necessarily a parallelogram. While opposite angles being congruent is a property of parallelograms, other quadrilaterals can also have congruent opposite angles.</p> Signup and view all the answers

In a parallelogram, consecutive angles are ______.

<p>supplementary</p> Signup and view all the answers

Which of the following conditions is sufficient to prove that a quadrilateral is a parallelogram?

<p>One pair of opposite sides is congruent and parallel (D)</p> Signup and view all the answers

Which of the following conditions is NOT a requirement for a quadrilateral to be a parallelogram?

<p>All four angles are right angles. (D)</p> Signup and view all the answers

If two opposite angles in a quadrilateral are congruent, then the quadrilateral must be a parallelogram.

<p>True (A)</p> Signup and view all the answers

What is the sum of two consecutive angles in a parallelogram?

<p>180 degrees</p> Signup and view all the answers

A parallelogram can be divided into two congruent ______ by drawing a diagonal.

<p>triangles</p> Signup and view all the answers

Match each property with the corresponding characteristic that guarantees a quadrilateral is a parallelogram:

<p>Opposite sides are congruent = Two pairs of opposite sides are congruent. Opposite angles are congruent = The two sets of opposing angles are congruent. Diagonals bisect each other = The two diagonals bisect each other. Consecutive angles are supplementary = Any two angles that share the same side in a parallelogram are supplementary.</p> Signup and view all the answers

Which of the following is TRUE about the diagonals of a parallelogram?

<p>They always bisect each other. (D)</p> Signup and view all the answers

If a quadrilateral has two pairs of congruent sides, it must be a parallelogram.

<p>False (B)</p> Signup and view all the answers

What is the term used to describe the point where the diagonals of a parallelogram intersect?

<p>midpoint</p> Signup and view all the answers

If a quadrilateral has two adjacent angles that are ______, then it must be a parallelogram.

<p>supplementary</p> Signup and view all the answers

The diagonals of a rhombus bisect each other.

<p>True (A)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a rectangle?

<p>All sides are congruent (C)</p> Signup and view all the answers

In parallelogram RUBY, ∠R = 115°. What is the measure of ∠U?

<p>65°</p> Signup and view all the answers

A quadrilateral with two pairs of congruent sides is a ______.

<p>parallelogram</p> Signup and view all the answers

Match the special parallelograms to their defining characteristics:

<p>Rhombus = All sides are congruent Rectangle = All angles are right angles Square = All sides are congruent and all angles are right angles</p> Signup and view all the answers

If the diagonals of a quadrilateral bisect each other, what type of quadrilateral must it be?

<p>Parallelogram (B)</p> Signup and view all the answers

In parallelogram ROAD, RM = 2y - 1 and MA = y + 2. Solve for y.

<p>y = 3</p> Signup and view all the answers

A parallelogram with one right angle is a square.

<p>False (B)</p> Signup and view all the answers

The diagonals of a rectangle are ______.

<p>congruent</p> Signup and view all the answers

Flashcards

Quadrilateral

A closed plane figure with four sides and four angles.

Convex Quadrilateral

A quadrilateral where the diagonals intersect.

Parallelogram

A quadrilateral with both pairs of opposite sides parallel.

Properties of Parallelogram

Opposite sides and angles are congruent; diagonals bisect each other.

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Opposite Sides

Sides that are across from each other in a quadrilateral.

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Consecutive Angles

Angles that are next to each other in a quadrilateral.

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Diagonals

Segments that connect opposite vertices in a quadrilateral.

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Parallelogram Conditions

A quadrilateral is a parallelogram if it meets specific angle and side criteria.

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Opposite Angles Congruent

In a parallelogram, the opposite angles are equal: ∠R ≅ ∠Y and ∠B ≅ ∠U.

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Supplementary Adjacent Angles

Adjacent angles in a parallelogram add up to 180 degrees; e.g., m∠R + m∠U = 180.

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Diagonal Bisection

In a parallelogram, the diagonals bisect each other at their midpoints.

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Matching Triangles

A diagonal of a parallelogram creates two congruent triangles.

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Opposite Sides Parallel

If one set of opposite sides is equal, the other set must be parallel (RU || BY).

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Angle Relationships

Two angles sharing a side in a parallelogram are supplementary.

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Congruent Opposite Angles

If two opposite angles are congruent, the shapes are similar (RB ≅ UY).

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Diagonal Midpoint

In a parallelogram, diagonals intersect at their midpoints, indicating symmetry.

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Rhombus

A parallelogram with four congruent sides.

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Rectangle

A parallelogram with four right angles.

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Square

A parallelogram with four congruent sides and four congruent angles.

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Conditions for Parallelogram

Equal opposite sides, one pair of congruent and parallel sides, diagonals bisecting, equal opposite angles, or consecutive angles summing to 180 degrees.

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Supplementary Angles

Two angles that add up to 180 degrees.

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Opposite Angles

Angles that are across from each other in a polygon.

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Diagonals of Parallelogram

The two line segments that connect opposite corners, bisecting each other.

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Theorem of Right Angles

If a parallelogram contains a right angle, then it is a rectangle.

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Study Notes

Quadrilaterals

  • A quadrilateral is a closed plane figure with four sides and four angles.
  • A convex quadrilateral has intersecting diagonals.
  • A non-convex quadrilateral has non-intersecting diagonals.
  • Parallel lines are lines that never intersect.
  • Intersecting lines are lines that cross each other.

Parallelograms

  • A parallelogram is a quadrilateral with both pairs of opposite sides parallel.
  • Opposite sides are congruent (equal in length).
  • Opposite angles are congruent.
  • Consecutive angles are supplementary (add up to 180 degrees).
  • Diagonals bisect each other.

Special Parallelograms

  • Rectangle: A parallelogram with four right angles.
  • Rhombus: A parallelogram with four congruent sides.
  • Square: A parallelogram with four congruent sides and four right angles.
  • A trapezoid is a quadrilateral with at least one pair of parallel sides
  • A trapezium is a quadrilateral with no parallel sides.
  • A kite is a quadrilateral with two pairs of adjacent sides that are congruent.

Theorems

  • Equal opposite sides are sufficient for a quadrilateral to be a parallelogram.
  • A single pair of congruent and parallel sides is sufficient to classify a quadrilateral as a parallelogram.
  • Diagonals that bisect each other are sufficient to identify a quadrilateral as a parallelogram.
  • A quadrilateral with equal opposite angles is always a parallelogram.
  • A quadrilateral with any two consecutive angles adding up to 180 degrees is a parallelogram.

Diagonals

  • Diagonals of a parallelogram bisect each other.
  • Diagonals of a square are perpendicular and equal in length
  • Diagonals of a rectangle are equal in length
  • Diagonals of a rhombus are perpendicular.

Properties of Special Parallelograms (Theorems)

  • A square's diagonals are perpendicular and are equal in length.

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