2.8 Proportions and Similarity

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you set up a proportion for a scale map?

Back

To set up a proportion for a scale map, use the formula: (map distance)/(actual distance) = (scale distance)/(scale actual distance).

Front

If the scale on a map is 0.75 in. : 10 miles, how do you find the map distance for 80 miles?

Back

Set up the proportion: (map distance)/(80 miles) = (0.75 in.)/(10 miles). Solve for map distance.

Front

What is the formula to find the perimeter of a rectangle?

Back

The perimeter P of a rectangle is given by P = 2(length + width).

Front

If a room's scale is 2.5 in. : 35 ft, how do you convert the drawing dimensions to actual dimensions?

Back

Use the proportion: (drawing dimension)/(actual dimension) = (2.5 in.)/(35 ft).

Front

What does it mean for two figures to be similar?

Back

Two figures are similar if their corresponding angles are equal and their corresponding sides are in proportion.

Front

How do you find the missing length in similar figures?

Back

Set up a proportion using the lengths of corresponding sides and solve for the missing length.

Front

What is the scale factor in a proportion?

Back

The scale factor is the ratio of the lengths of two corresponding sides of similar figures.

Front

How do you calculate the actual distance using a map scale?

Back

Multiply the map distance by the scale factor to find the actual distance.

Front

What is the relationship between scale and distance in a map?

Back

The scale indicates how much distance on the ground is represented by a certain distance on the map.