Answer:
-2-√3
Step-by-step explanation:
The sum of angles formula for tangent is ...
tan(A+B) = (tan(A) +tan(B))/(1 -tan(A)tan(B))
For the desired angle, we can use A=45°, B=60°. Then we have ...
tan(105°) = (tan(45°) +tan(60°))/(1 -tan(45°)tan(60°))
The tangent values we need are ...
tan(45°) = 1
tan(60°) = √3
Then our tangent is ...
tan(105°) = (1 +√3)/(1 -1·√3) = (1 +√3)²/((1 -√3)(1 +√3)) = (4+2√3)/(-2)
tan(105°) = -(2+√3)
