Ratios, Proportions, and Scale Factors

Front

What is a ratio?

Back

A ratio is a comparison of two quantities by division, expressed as a fraction, decimal, or with a colon (e.g., 3:2).

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal (e.g., a/b = c/d).

Front

What is a scale factor?

Back

A scale factor is a number that scales, or multiplies, some quantity. It is the ratio of the lengths of two corresponding sides of similar figures.

Front

If Square A is a dilation of Square B with a scale factor of 5/4, what does this mean?

Back

It means that each side of Square A is 5/4 times the length of the corresponding side of Square B.

Front

How do you find the perimeter of a triangle given the lengths of its sides?

Back

Add the lengths of all three sides together.

Front

If the sides of a triangle are in the ratio 3:4:5, and the shortest side is 6, what are the lengths of the other sides?

Back

The lengths of the other sides are 8 and 10.

Front

What is the relationship between similar figures and scale factors?

Back

Similar figures have the same shape but different sizes, and the scale factor is the ratio of corresponding side lengths.

Front

How do you solve for x in a proportion?

Back

Cross-multiply the terms and then solve for x.

Front

If 2/3 = x/12, what is the value of x?

Back

x = 8.

Front

What is the formula for finding the scale factor between two similar triangles?

Back

Scale factor = length of a side in the first triangle / length of the corresponding side in the second triangle.