Answer:
F = 53.1°
Step-by-step explanation:
When you consider F as your angle
cos F = adjacent / hypotaneous
or, cos F = EF/DF
We do not have DF right now,
so DF² = DE² + EF²
DF = √ (12² + 9²)
DF = 15
cos F = adjacent / hypotaneous
or, cos F = EF/DF
cos F = 9 / 15
F = cos ⁻¹ (9/15)
F = 53.1°
