Problem
Here is triangle DEF. Find the value of each trigonometric ratio: \[ \cos (D)= \] \[ \tan (F)= \]
Solution
Step 1 ：Given triangle DEF, identify known sides and angles.
Step 2 ：Calculate \cos(D) using the values of adjacent side and hypotenuse.
Step 3 ：Calculate \tan(F) using the values of opposite side and adjacent side.
