Correct Answer - Option 3 : -
\(\frac{1}{\sqrt 3}\)
Concept:
Some useful formulas are,
tan (360° ± x) = tan x
tan (90°+ x) = - cot x
Calculation:
tan (1230°) can be written as,
tan (3 × 360° + 150°)
= tan (150°) [∵ tan (360° ± x) = tan x]
= tan ( 90° + 60°)
= - cot 60°
= - \(\rm 1\over \sqrt3{}\)