Triangle ABC is similar to triangle DEF. To one decimal place calculate the value of x.

http://curriculum.kcdistancelearning.com/courses/GEOMx-HS-WA10/b/assessments/S-SimilarTrianglesQuiz/Geometry_6.2_Quiz_FINAL_29q.gif

I don't get how to do this..

Question

Triangle ABC is similar to triangle DEF. To one decimal place calculate the value of x.

http://curriculum.kcdistancelearning.com/courses/GEOMx-HS-WA10/b/assessments/S-SimilarTrianglesQuiz/Geometry_6.2_Quiz_FINAL_29q.gif

I don't get how to do this..

anonymous · Answer

for similar triangle the corresponding sides are in the same proportion. i.e corresponding ratios are the same:

For the above triangles:
AB/DE = AC/DF =BC/EF.

Therefore since x is  DF, can pick:
 AC/DF =BC/EF  

i.e. 13/x=5/4
 =>  x=52/5 =10.4