Question

The pair of figures is similar. Find x. Round to the nearest tenth if necessary.

Answer 1

23/x = 40/17
23(17) = 40x
391/40 = x
9.775 = x

Answer 2

The pair of triangle shown in the diagram are similar. Similar triangle have proportional corresponding sides. So you can write a proportion connecting all given known and unknown sides:

$\dfrac{23}{40}=\dfrac{x}{17}.$

From here you have that

$40\cdot x=23\cdot 17,\\ \\x=\dfrac{23\cdot 17}{40}=\dfrac{391}{40}=9.775\approx 9.8\ cm.$

Answer: 9.8 cm.