Answer:
21.
Step-by-step explanation:
Answer:
CD = 14 cm; DE = 21 cm
Step-by-step explanation:
The perimeter is the sum of side lengths (in centimeters), so ...
CD + DE + CF + EF = 55
CD + DE + 8 + 12 = 55 . . . . . . . substittute for CF and EF
CD + DE = 35 . . . . . . . . . . . . . . subtract 20
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The segment DF is a diagonal of the rhombus, so bisects angle D. That angle bisector divides ΔCDE into segments that are proportional. That is, ...
CD/DE = CF/EF = 8/12 = 2/3
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So, we have two segments whose sum is 35 (cm) and whose ratio is 2 : 3. The total of "ratio units is 2+3=5, so each must stand for a length unit of 35/5 = 7 (cm). The sides are ...
CD = 2·7 cm = 14 cm
DE = 3·7 cm = 21 cm
<em>Check</em>
CD + DE = (14 +21) cm = 35 cm . . . . . matches requirements
if there were 100 questions then 76 were correct, and 24 incorrect, you can simplify and rearrange the fraction depending on how many questions there were,
10 because if you 3 with 7 I will make 10
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