Answer:
D) cos^-1 (f/e)
Explanation:
Since you only know two sides, DE = f, and DF = e, you need to use cosine to find the measure of ∠D.
Let x represent m∠D
cos x = f/e
To find x, take the inverse of cos, so:
cos^-1 (f/e) = x
4.7m questions
6.1m answers