See what answer can you get from the problem below — the question appears in an older version of a very popular math book: “Math Smart — Canadian Curriculum”.
Now check with your friend about his / her answer. If the two answers (yours and your friend’s) does not agree, you are not alone.
Say, Jack insisted that in the middle part (by dropping two vertical lines from the two ends of the top to the bottom) there is a square (or at least it’s a rectangle), and the colored part – the green triangle is one-quarter of the total area of the square / rectangle. Do you agree with him?
Since Mary cannot find agreement with Jack, she suspect that the middle part should not be a square / rectangle. — Well, the diagram might not be that perfect to be a square, or not even a rectangle. Do you think that Mary has a point?
Even though this seems easy — only calculation of the area, but we find people cannot agree on one answer. Should we rely on the accurate drawing of a figure to work on a geometric problem?