Can you show me how to set up the proportion?

Step-by-step explanation:

First of all, write the similarity statement for the triangles.

  ΔCDE ~ ΔCBA

Identify the line segments in each triangle that you know. Preferably, choose ones that correspond.

  CE = 27, DE = the length we want to find . . . . known segments in ΔCDE

  CA = (18+27) = 45 . . . . . corresponds to CE

  BA = 28 . . . . . . . . . . . . . corresponds to DE

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The ratios of corresponding line segments are equal:

  DE/CE = BA/CA . . . . this is the proportion you want to set up*

  DE/27 = 28/45

Multiply by the denominator of DE/27 to eliminate that:

  DE = 27(28/45)

  DE = 16.8

* I usually choose to put the unknown variable in the numerator of a proportion, so that solving it only involves multiplication by the denominator. If you put the variable in the denominator, the solution takes an extra step.

circle area = pi * radius^2

if diameter = 10 then radius = 5

circle area = pi * 5^2

circle area = pi * 25

circle area = 78.5398163397 square units

step-by-step explanation:

the answer to your question is c.)   volcanoes built the mountains and earthquakes tore them down.

step-by-step explanation: