A. Corresponding parts of similar triangles are similar.
B. Alternate interior angles are supplementary.
C. Alternate interior angles are congruent.
D. Corresponding parts of congruent triangles are congruent
1. Opposite sides are parallel 2. Corresponding parts of congruent triangles are congruent
A basic knowledge of angles when two parallel lines meet a transversal is necessary.
opposite sides are congruent corresponding parts of congruent triangles are congruent(apex)
A ruler or a compass would help or aternatively use Pythagoras' theorem to prove that the diagonals are of equal lengths
The diagonals divide the quadrilateral into four sections. You can then use the bisection to prove that opposite triangles are congruent (SAS). That can then enable you to show that the alternate angles at the ends of the diagonal are equal and that shows one pair of sides is parallel. Repeat the process with the other pair of triangles to show that the second pair of sides is parallel. A quadrilateral with two pairs of parallel lines is a parallelogram.
1. Opposite sides are parallel 2. Corresponding parts of congruent triangles are congruent
A basic knowledge of angles when two parallel lines meet a transversal is necessary.
Because its 4 interior angles must add up to 360 degrees
To prove that the opposite angles of a parallelogram are congruent, you can utilize the properties of parallel lines and transversals. Since the opposite sides of a parallelogram are parallel, the alternate interior angles created by a transversal are equal. Additionally, you can apply the fact that consecutive angles in a parallelogram are supplementary, leading to the conclusion that if one angle is known, its opposite angle must be equal. Thus, through these properties, you can establish that opposite angles are congruent.
opposite sides are congruent corresponding parts of congruent triangles are congruent(apex)
To prove that the opposite sides of a parallelogram are congruent, you need to establish that the shape is a parallelogram, which can be done by showing that either pairs of opposite sides are parallel (using the properties of parallel lines) or that the diagonals bisect each other. Additionally, applying the properties of congruent triangles (such as using the Side-Side-Side or Side-Angle-Side postulates) can further support the proof. Ensure to use clear definitions and properties of parallelograms throughout the proof.
Always. In fact, one method of proving a quadrilateral a rhombus is by first proving it a parallelogram, and then proving two consecutive sides congruent, diagonals bisecting verticies, etc.
A description that states a quadrilateral has one pair of opposite sides that are both equal and parallel does not guarantee that it is a parallelogram. While this condition is sufficient for proving that a quadrilateral is a parallelogram, it is not necessary; other configurations might exist where a quadrilateral meets this condition without being a parallelogram. Other descriptions, such as having both pairs of opposite sides equal or both pairs of opposite angles equal, would guarantee it is a parallelogram.
It is helpful (not help full) because the two triangles formed by either diagonal are congruent.
In a parallelogram, the diagonals bisect each other, meaning they cut each other exactly in half at their intersection point. Additionally, while the diagonals are not necessarily equal in length, they do divide the parallelogram into two congruent triangles. This property is fundamental in proving various characteristics of parallelograms and is essential in geometry.
A ruler or a compass would help or aternatively use Pythagoras' theorem to prove that the diagonals are of equal lengths
First draw a parallelogram. I cannot draw one here so I will have to describe the picture and you should draw it. Let ABCD be a parallelogram. I put A on the bottom left, then B on the bottom right, C on the top right and D on the top left. Of course the arguments must apply to an arbitrary parallelogram, but just so you can follow the proof, that is my drawing. Now draw a segment from A to C. It is a diagonal. AB is parallel to CD and AD is parallel to BD because a parallelogram is a quadrilateral with both pair of opposite sides parallel. Now ABC and CDA both form triangles. Let angles 1 and 4 be the angles created by the diagonal and angle BCD of the parallelogram. Angle 1 is above and angle 4 is below. Similarly, let angles 3 and 2 be created by the intersection of the diagonal and angle DAB or the original parallelogram. Now angles 1 and 2 are congruent as are 3 and 4 because if two parallel lines are cut by a transversal, the alternate interior angles are congruent. Next using the reflexive property AC is congruent to itself. Now triangle ABC is congruent to triangle CDA by Angle Side Angle (SAS). This means that AB is congruent to CD and BC is congruent to AD by corresponding parts of congruent triangles are congruent (CPCTC). So we are done!