29/50 or 0.58 is the answer
Remember the notation..
When you have a triangle called ABD, the angles may be called in theses equivalent ways>
angle A is equivalent to ∠ DAB
angle B is equivalent to ∠ ABD
angle D is equivalen to ∠ BDA
Then given that the two triangles are congruent, you can say an
angle B = angle F = ∠ EFC
So the answer is the last option of the list.
Multiply 5 by 9.8 to get the answer.
This would be about 13 cm
Hope this helps explain what was needed to be solved! :)