standard_description: Prove theorems about parallelograms. Theorems include: opposite sides are congruent, opposite angles are congruent, the diagonals of a parallelogram bisect each other, and conversely, rectangles are parallelograms with congruent diagonals.
problem_activity: Task
Write as many equations for each picture as you can.
Use the numbers 4, 1, and 5.
[IMG]
Here are some equations for this picture. $$4+1=5 \hskip4em 5 = 4+1$$ $$5-1=4 \hskip4em 4=5-1$$ Can you find more equations?
Use the numbers 3, 5, and 8.
[IMG]
Use the numbers 4, 4, and 8.
[IMG]
Use the numbers 4, 5, and 9.
[IMG]
Draw your own picture and write all the equations you can think of to describe it.


aligns: no