Question

how long is the side labeled x? 9 12 3 4 5 o 18 units o 15 units o 13 units o 19 units

Explanation:

Step1: Identify similar triangles

The two triangles are similar since the ratios of corresponding sides are equal. $\frac{9}{3}=\frac{12}{4} = 3$.

Step2: Set up proportion

Let the sides of the first triangle be $a = 9$, $b = 12$, $c=x$ and the sides of the second triangle be $a'=3$, $b' = 4$, $c'=5$. Since they are similar, $\frac{x}{5}=3$.

Step3: Solve for x

Multiply both sides of the equation $\frac{x}{5}=3$ by 5. So $x=3\times5 = 15$ units.

Answer:

B. 15 units