Question

Without using a calculator how do you evaluate tan 5π/6.

Answer 1

Remember that pi=180, 
so 180/6=30, 30*5=150,
what's tan 150? 
Remember that 150 degrees is in the 2nd quadrant, and this is tangent, so it means the answer must be negative, because tan 150= - tan 30, and -tan30=-√3/3. 

Answer: -√3/3.