Aside from points, as we have discussed in the previous post, the other two undefined terms in Geometry are *lines* and *planes*. A line may be drawn through two points, while three points are needed to determine a plane. The representations of these undefined terms are the building blocks of *Euclidean Geometry. * They can be combined to create shapes, drawings, and sketches such as the painting shown in the first figure. Looking at the painting makes us realize that almost all the things around us are mostly basic geometric shapes.

In the painting above, we can easily see geometric shapes such as rectangles, triangles, trapezoids , and parallelograms. We can also see curves and arcs in vases, flowers, and fruits. Notice that although the painting seems to be only made by these shapes, the artist has made it look very realistic. For example, the window frames located at the left side of the painting are of the same size, but the artist made the ‘nearer’ frame larger to give a somewhat three dimensional effect. In doing so, the painter considered the distance of the window frames from the *observer*. The farther the frame, the smaller its size. Observe that this technique is more apparent in the painting by Vincent Van Gogh in the second figure. Continue reading →