Question

in the figure, triangle RED is similar to triangle RSF what is the value of x, the length of side RS

Answer 1

Since the triangles are similar thie means that:

$\frac{8}{x}=\frac{12}{21}$

Solving for x we have:

$\begin{gathered} \frac{8}{x}=\frac{12}{21} \\ 8=\frac{12}{21}x \\ x=\frac{8}{\frac{12}{21}} \\ x=\frac{21\cdot8}{12} \\ x=\frac{168}{12} \\ x=14 \end{gathered}$

Therefore x=14