Two figures are said to be SIMILAR if they are the same shape. In more mathematical language, two figures are similar if their corresponding angles are congruent , and the ratios of the lengths of their corresponding sides are equal. This common ratio is called the scale factor.

Each pair of figures is similar. Find the value of the missing side (x). Round your answer to the nearest tenth if necessary. 12in 10in 8in xin
A.6.7in
B.5in
C.6in
D.7in
Best answer

1 answer

To find the missing side \( x \) in the similar figures, we can use the property that the ratios of the lengths of corresponding sides are equal.

From the given dimensions, we denote the sides of the first figure as \( 12 , \text{in}, 10 , \text{in}, \) and \( 8 , \text{in} \). The corresponding side in the second figure is \( x \).

To find the relationship, we can set up the proportion using any two corresponding sides. Let's use the side lengths \( 12 , \text{in} \) and \( x \):

\[ \frac{12}{x} = \frac{10}{8} \]

Now, we can simplify the ratio on the right side:

\[ \frac{10}{8} = \frac{5}{4} \]

So the equation becomes

\[ \frac{12}{x} = \frac{5}{4} \]

Next, we cross-multiply to solve for \( x \):

\[ 12 \cdot 4 = 5 \cdot x \] \[ 48 = 5x \] \[ x = \frac{48}{5} \] \[ x = 9.6 \]

Since 9.6 is not among the provided options, let's check the ratios between other corresponding pairs, for instance, \( 10 , \text{in} \) and \( x \):

Setting up the proportion with \( x \):

\[ \frac{10}{x} = \frac{8}{6} \quad \text{(if we assume another set of corresponding values)} \]

Now simplify:

\[ \frac{10}{x} = \frac{4}{3} \]

Cross-multiplying gives:

\[ 10 \cdot 3 = 4 \cdot x \] \[ 30 = 4x \] \[ x = \frac{30}{4} = 7.5 \]

Since \( 7.5 \) is not listed and is closest to \( 7 \) from options, we can check one more option using ratios:

Using \( 8 \) and \( x \) again with the reference:

\[ \frac{8}{x} = \frac{12}{10} \] \[ \frac{8}{x} = \frac{6}{5} \] Cross-multiplying:

\[ 8 \cdot 5 = 6 \cdot x \] \[ 40 = 6x \] \[ x = \frac{40}{6} \approx 6.67 \]

So the answer rounds to \( 6.7 \), which matches with the option A:

Answer: A. 6.7 in