Answer:
DE ≈ 6.97
Step-by-step explanation:
Using the cosine ratio in the right triangle
cos55° = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{EF}{DE}[/tex] = [tex]\frac{4}{DE}[/tex] ( multiply both sides by DE )
DE × cos55° = 4 ( divide both sides by cos55° )
DE = [tex]\frac{4}{cos55}[/tex] ≈ 6.97 ( to the nearest hundredth )
