Main content

Transformations & congruence

Learn
Congruent shapes & transformations
(Opens a modal)
Non-congruent shapes & transformations
(Opens a modal)
Practice
Congruence & transformationsGet 3 of 4 questions to level up!

Triangle congruence

Learn
Congruent triangles & the SSS postulate/criterion
(Opens a modal)
Triangle congruence postulates/criteria
(Opens a modal)
Why SSA isn't a congruence postulate/criterion
(Opens a modal)
Determining congruent triangles
(Opens a modal)
Triangle congruence review
(Opens a modal)
Practice
Determine congruent trianglesGet 5 of 7 questions to level up!

Theorems concerning triangle properties

Learn
Angles in a triangle sum to 180° proof
(Opens a modal)
Proofs concerning isosceles triangles
(Opens a modal)
Proofs concerning equilateral triangles
(Opens a modal)

Working with triangles

Learn
Corresponding angles in congruent triangles
(Opens a modal)
Isosceles & equilateral triangles problems
(Opens a modal)
Finding angles in isosceles triangles
(Opens a modal)
Finding angles in isosceles triangles (example 2)
(Opens a modal)
Practice
Find angles in congruent trianglesGet 3 of 4 questions to level up!
Find angles in isosceles trianglesGet 3 of 4 questions to level up!

Theorems concerning quadrilateral properties

Learn
Proof: Opposite sides of a parallelogram
(Opens a modal)
Proof: Diagonals of a parallelogram
(Opens a modal)
Proof: Opposite angles of a parallelogram
(Opens a modal)
Proof: The diagonals of a kite are perpendicular
(Opens a modal)
Proof: Rhombus diagonals are perpendicular bisectors
(Opens a modal)
Proof: Rhombus area
(Opens a modal)

Proofs of general theorems that use triangle congruence

Learn
Geometry proof problem: midpoint
(Opens a modal)
Geometry proof problem: congruent segments
(Opens a modal)
Geometry proof problem: squared circle
(Opens a modal)

Constructing bisectors of lines & angles

Learn
Geometric constructions: perpendicular bisector
(Opens a modal)
Geometric constructions: perpendicular line
(Opens a modal)
Geometric constructions: angle bisector
(Opens a modal)

About this unit

Learn what it means for two figures to be congruent, and how to determine whether two figures are congruent or not. Use this immensely important concept to prove various geometric theorems about triangles and parallelograms.