Scale factor

Surface Area and Volume

Scale factor

Scale factor is a number that you multiply a measurement by to increase or decrease in size.

Scale factor• A scale factor is used to scale shapes in 1, 2, or 3 dimensions.• Scale factor can be found in the following scenarios:Size Transformation: In size transformation, the scale factor is the ratio of expressing the amount of magnification.

Scale Drawing: In scale drawing, the scale factor is the ratio of measurement of the drawing compared to the measurement of the original figure.

Comparing Two Similar Geometric Figures: The scale factor when comparing two similar geometric figures, is the ratio of lengths of the corresponding sides.

9cm

9cm

3 times bigger

3cm

3cm Actual

ScaleImage

Scale factor =

Scale factor calculation

• If decimal value is more than one it is an enlargement

• If decimal value is less than one it is a reduction

Applying Scale Factor• Applying a scale factor of 3:5 to rectangle

• Would the scaled image be an enlargement or a reduction• Reduction

• What would the dimensions be of the new image. • To find dimensions multiply each of the

dimensions with the scale factor

7.4cm

2.2cm

Ratio of area• Find the ratio of the lengths of sides• Square the ratio to find the ratio of the surface

areas

b

ca

5cm

e

fd

2cm

How surface area and volume are affected by scale factor

• Find the ratio of the LENGTHS of sides

• SQUARE the ratio to find the ratio of the surface areas

• CUBE the ratio of lengths to find the ratio of the volume.

4cm

A2cm

B

https://www.mrperezonlinemathtutor.com/CARFILES/Similarity_Triangles_Enlargement_Reduction_by_Scaled_Factor.html

http://www.slideboom.com/presentations/53232/Surface-Area-and-Volume-of-Similar-Solids.