Answer: 13.48 degrees
This answer is approximate to 2 decimal places
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To get this answer, we have to note how DE = 52 is the side opposite angle DFE and DF = 223 is the hypotenuse. The trig function relating the opposite and hypotenuse is the sine function.
sin(angle) = opposite/hypotenuse
sin(angle DFE) = DE/DF
sin(angle DFE) = 52/223
Now we use the arcsine function to figure out what angle DFE is
sin(angle DFE) = 52/223
angle DFE = arcsin(52/223)
angle DFE = 13.48459
angle DFE = 13.48