**parallelogram**. If — AB ≅ — CD and — BC ≅ — DA , then

**ABCD is a parallelogram**. If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a

**parallelogram**.

### what theorem or postulate is used to prove ABCD is a parallelogram?

Proof: Given ABCD, let the diagonals AC and BD intersect at E, we must prove that AE ∼ = CE and BE ∼ = DE. The converse is also true: If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram. Theorem: Opposite angles of a parallelogram are **congruent** to each other.

### what are the 6 ways to prove a quadrilateral is a parallelogram?

**Terms in this set (6)**

### Is a square a rhombus?

A rhombus is a quadrilateral with all sides equal in length. A square is a quadrilateral with all sides equal in length and all interior angles right angles. Thus a rhombus is not a square unless the angles are all right angles. A square however is a rhombus since all four of its sides are of the same length.

### how do you prove a figure is a parallelogram?

**To prove a quadrilateral is a parallelogram, you must use one of these five ways.**

### How do you prove a rectangle is a parallelogram?

How to Prove that a Quadrilateral Is a Rectangle If all angles in a quadrilateral are right angles, then it’s a rectangle (reverse of the rectangle definition). If the diagonals of a parallelogram are congruent, then it’s a rectangle (neither the reverse of the definition nor the converse of a property).

### How can you prove that a quadrilateral is a parallelogram when using the coordinate plane?

To **prove** that it is a **parallelogram**, remember that the definition of a **parallelogram** is a **quadrilateral** with two pairs of parallel sides. Therefore, one way to **prove** it is a **parallelogram** is to verify that the opposite sides are parallel. From algebra, remember that two lines are parallel if they have the same slope.

### How do you prove lines are parallel?

The first is if the corresponding angles, the angles that are on the same corner at each intersection, are equal, then the lines are parallel. The second is if the alternate interior angles, the angles that are on opposite sides of the transversal and inside the parallel lines, are equal, then the lines are parallel.

### Is rhombus a parallelogram?

DEFINITION: A rhombus is a parallelogram with four congruent sides. THEOREM: If a parallelogram is a rhombus, each diagonal bisects a pair of opposite angles. THEOREM Converse: If a parallelogram has diagonals that bisect a pair of opposite angles, it is a rhombus.

### What does it mean to be congruent?

Congruent. Angles are congruent when they are the same size (in degrees or radians). Sides are congruent when they are the same length.

### What kind of quadrilateral is ABCD?

Definition A convex quadrilateral ABCD is called a ˆ parallelogram if the opposite sides AB, CD and BC, AD are parallel.

### Is a trapezoid a parallelogram?

A Trapezoid is a quadrilateral with one pair of parallel sides. To be clear a trapezoid has exactly one pair of parallel sides. A trapezoid is not a parallelogram. A parallelogram is a quadrilateral with two pairs of parallel sides.

### What is Cpctc Theorem?

CPCTC is an acronym for corresponding parts of congruent triangles are congruent. CPCTC is commonly used at or near the end of a proof which asks the student to show that two angles or two sides are congruent. Corresponding means they’re in the same position in the 2 triangles.

### Is a kite a parallelogram?

Explanation: A kite is a quadrilateral with two disjoint pairs (no side is in both pairs) of equal-length, adjacent (sharing a vertex) sides. A parallelogram also has two pairs of equal-length sides, however they must be opposite, as opposed to adjacent.