All three of them are significant figures
They can be measured by their linear measures in three orthogonal directions.
length times(x) width * * * * * Very few 2-dimensional figures are measured by length and width - rectangles (and stretching the terminology) triangles and parallelograms. Certainly not circles, stars, irregular polygons, other irregular shapes.
Surface area of three dimensional figures are measured in square units whereas their volumes are measured in cubic units
The simple rule is: no more significant figures than the least accurate of the values in the computation. For multiplication and division, the result should have as many significant figures as the measured number with the smallest number of significant figures. For addition and subtraction, the result should have as many decimal places as the measured number with the smallest number of decimal places. (Rounding off can be tricky, but that would be another thread)
A sphere.
4 significant figures.
All three of them are significant figures
They can be measured by their linear measures in three orthogonal directions.
Area; this is often measured in square meters, or square centimeters.
significant figures.
Length Width
Length And Width
4
28.71
3.774 is to 4 significant figures (count them)
Answer for Apex: length, width, and height