### Chap 12: Can you tell if ABCD is a parallelogram?

1. It is a parallelogram.
This is because the shape has two pairs of parallel lines.

1. How did you deduce that?
I deduce that by looking at the distance of the lines. This was by looking at the grids that they cut through. I also deduce that by seeing how the lines cut through the grids.For example,the lines cut through and form two triangles which are of the same area. So, this means that the line cuts through the grid exactly into halves.

2. This can also be deduced by calculating the leftover are and comparing them if they are the same.

2. This comment has been removed by the author.

3. ABCD is a parallelogram. I used a set square and found that the quadrilateral ABCD has two sets of parallel lines. Hence, ABCD is a parallelogram.

4. it is. This is because that the breadth and the length are the same, so they are parallel to each other.

1. And it has two pairs of the parallel lines in this diagram.

5. I think that ABCD is a parallelogram. I placed my ruler against the lines and found that both sets were parallel. ._.

6. Yes,it is a parallelogram.

Parallelogram has two parallel sides. [AB //DC] and [AD // BC].Thus, abcd is a parallelogram

7. No, because we do not know what is the value of a and b and we cannot assume.
We can check if it is a parallelogram by using a protractor to measure angle b and d. a parallelogram has equal opposite angles. If both angles are the same, it is a parallelogram.

8. As a parallelogram has 2 pair of parallel lines, thus this is not a parallelogram. Thus, by using a ruller, I saw that the line above and below is not parallel to one another.

1. Zit' 's called ze' rula'(ruler).

2. oh, I zizn't znow that

9. ABCD is a parallelogram as I placed my ruler and found that the distances between the lines are equal.

10. Yes. It is formed by 2 sets of parallel lines.
BC//cD - Both lines meet a point every square (45 degrees)
aB//DC - Both lines meet a point every 2 squares(22.5)
Parallellogram - In Euclidean geometry, a parallelogram is a simple (non self-intersecting) quadrilateral with two pairs of parallel sides. The opposite or facing sides of a parallelogram are of equal length and the opposite angles of a parallelogram are of equal measure.
Therefore, both sets of lines are parallel, and the length of each set of parallel lines are equal.

11. It is a parallelogram.
It has 2 pairs of parallel lines. BC=AD and CD=BA

12. Yes. I think it is a parallelogram as it has two pairs of parallel lines as I made use of my ruler and placed it on the picture and confirmed it that it is a parallelogram.

13. Yes, it is a Parallelogram. Line AD is parallel to Line BC as they cut across 4units^2 squares (-2,-1 to 0,-3 and 0,3 to 2,1). AB and CD are also parallel as they cut across 2units^2 rectangles (-1,-1 to 0,1 and 1,-1 to 2,1). Therefore, there are 2 sets of parallel lines and it is a parallelogram.

14. It is a parallellogram because there is two pair of parallel lines (lines BC//AD which intercept the number 3 and 1.5 and lines BA//CD) (both lines are directly opposite to each other)

15. It is a parallelogram, as there are alternate angles present. Alternates angles are formed only with parallel lines.

16. It is a parallelogram, The lines are parallel.

17. It is a parallelogram as they have parallel lines and I used my protecter and saw the opposite angles are equal and I used my ruler and found that the distances are equal

18. Yes, it is a parallelogram as it has two sets of parellel lines CD,BA and BC, AD. This is so as the first set of parellel lines(CD and BA) are of equal length as the causing the set of parelel lines(BC and AD) to be proven as parellel lines. The second set of parellel lines(BC and AD) are of equal length as the causing the set of parelel lines(CD and BA) to be proven as parellel lines.

19. It is a parallelogram cuz it has two sets parallel lines and they are in fact parallel.Becuse lines ab and cd 2y=x and that lines ad and bc y=x or something like that.(i do not know how to explain)

20. After I used Geogebra, I found that:
-equation of Side AB: y = 2x+1
-equation of Side BC: y = -x-3
-equation of Side CD: y = 2x-3
-equation of Side DA: y = -x+3

Since the gradient of the sides AB & CD, as well as BC & AD, are equal, AB is parallel to CD, BC is parallel to AD.
Therefore ABCD is a parallelogram.