As the name suggestions, $3$3D drawings have three dimensions. They have a length, width and height, although sometimes the words width and depth are used as well.
In this $2$2D drawing of a rectangle I don't need to mark on all the measurements for all $4$4 sides because we can tell from the markings on the diagram that the side marked with an $a$a, will be of length $8$8cm.
Similarly in 3D drawings there is no need to mark on every dimension, just enough dimensions to be able to determine all relevent dimensions.
Here is an example of what I mean.
Examples
Question 1
Determine the dimensions indicated by $A$A and $B$B on the diagram.
The total width is $8$8cm, and we can see widths of $2$2cm and $4$4cm This means that A must be $2$2cm.
The total length is $15$15cm, and we can see sub-lengths of $5$5cm and $5$5cm already. This means that $B$B must also be $5$5cm in length.
As you can see the key to solving these problems is to identify all the lengths that are relevent - and don't be afraid to draw on the diagrams it actually can be a big help!
QUESTION 2
Given the object in the following figure.
Which of the following figures are identical to the original figure?
A
B
C
DIf the side of each cube measures $4$4mm, find the height, width, and depth.
Height: $\editable{}$mm
Width: $\editable{}$mm
Length: $\editable{}$mm
When comparing the object to the following solid, how many cubes have been cut away?
