Answer:
42.3
Explanation:
You want the length of side c opposite the 100° angle with sides 25 and 30 units in ∆ABC.
Law of cosines
The law of cosines formula is given as ...
c² = a² +b² -2ab·cos(C)
Using the given values, we find ...
c² = 25² +30² -2·25·30·cos(100°) ≈ 1785.47
c ≈ √1785.47 ≈ 42.3
The length of c is about 42.3 units.