Lessons for G.CO.C.11
Properties of a parallelogramOpposite sides are parallel and congruent, opposite angles are congruent, and neighboring angles are supplementary.Lesson
Proofs about parallelogramsCongruent triangles made by a diagonal supply almost every parallelogram property.Lesson
Proving a parallelogram is a rectangle or a rhombusCongruent diagonals or one right angle forces all four angles to be right.Lesson
Proving a quadrilateral is a parallelogramAny one of several conditions on the sides, the angles or the diagonals is enough.Lesson
Proving properties of a parallelogramOne diagonal splits the parallelogram into two congruent triangles.Lesson
The quadrilateral family treeHow square, rectangle, rhombus, parallelogram, trapezoid and kite sit inside one another.Lesson
Rectangles, rhombuses and squaresA parallelogram with four right angles, whose two diagonals are also equal in length.Lesson
Printable Worksheets
Properties of a parallelogram worksheet (PDF)Printable worksheet with answer keyPreview
Proving a parallelogram is a rectangle or a rhombus worksheet (PDF)Printable worksheet with answer keyPreview
Proving a quadrilateral is a parallelogram worksheet (PDF)Printable worksheet with answer keyPreview
Proving properties of a parallelogram worksheet (PDF)Printable worksheet with answer keyPreview
The quadrilateral family tree worksheet (PDF)Printable worksheet with answer keyPreview
Rectangles, rhombuses and squares worksheet (PDF)Printable worksheet with answer keyPreview