Class 7 Maths Visualising Solid Shapes Drawing Solids On a Flat Surface

Drawing Solids On a Flat Surface

We draw the surface of solids on a paper which is flat. The images of solids appear in such a way that they looks like three-dimensional. There are two techniques to draw it.

Oblique Sketches

Let us take an example of cube. The given picture shows how a cube looks like from the front. We are not able to see all the faces. Such a sketch of a solid is called an oblique sketch.

First, we take a squared paper. We draw an oblique sketch of a 3 * 3 * 3 cube i.e. each edge of cube is 3 units.

Step 1: Draw the front edge Step 2: Draw the opposite face having the same size in the left of faces in step 1. Step 3: Join the corresponding corners. Step 4: Redraw the hidden edges using blue lines. This is the sketch of cube.

Isometric Sketches:

Let we want to draw an isometric sketch of cuboid of dimension 4 * 3 * 3. We take an isometric dot sheet. This sheet divides the paper into small equilateral triangles made up of dots or lines.

Step 1: Draw a rectangle to show the front face. Step 2: Draw four parallel line segment of length 3 starting from the four corners of the rectangle. Step 3: Connect the corners with appropriate line segments. Step 4: This is an isometric sketch of the cuboid. Problem: Give (i) an oblique sketch and (ii) an isometric sketch for each of the following:

(a) A cuboid of dimensions 5 cm, 3 cm and 2 cm.         (b) A cube with an edge 4 cm long.

Solution:

(a) A cuboid of dimension 5 cm, 3 cm and 2 cm. (b) A cube with an edge 4 cm long. .