Question

7. Triangles CDE and RST are similar triangles. What is

the length of side CD in triangle CDE?
R
40 ft.
32 ft.
20 ft.
T
S

Answer 1

CD = 25 ft

Explanation:

Since the triangles are similar then the ratios of corresponding sides are equal, that is

`(CD)/(RS)` =
`(CE)/(RT)` , substitute values

`(CD)/(20)` =
`(40)/(32)` ( cross- multiply )

32CD = 800 ( divide both sides by 32 )

CD = 25

Answer 2

CD = 25 ft

Explanation:

`\triangle CDE \sim \triangle RST`

`\therefore (CD)/(20)=(40)/(32)`

(Corresponding sides of similar triangles are in proportion)

`\therefore (CD)/(20)=(5)/(4)`

`\therefore CD = (5)/(\cancel 4)* \cancel {20} \:\:\blue{\bold{5}}`

`\therefore CD = 5* 5`

`\therefore CD = 25\: ft`