If tanA+tanB+tanC=tanA·tanB·tanC then conclude about A,B,C.
Use tangent of sum of angle formula
Given, tanA+tanB+tanC=tanA·tanB·tanC
from the standard formula,
⇒tanA+B+C=tanA+tanB+tanC-tanA·tanB·tanC1-tanA·tanB-tanA·tanC-tanB·tanC
Since tanA+tanB+tanC=tanA·tanB·tanC
⇒tanA+B+C=0⇒A+B+C=tan-1(0)⇒A+B+C=nπ
If n=1,
⇒A+B+C=180°.
Therefore, sum of A, B and C is an integral multiple of π.
If, then what can be concluded about the vector?