Question

Cos (11 pi /9) state the signs of trigonometric functions

Answer 1

hi,

Cos (11 pi /9)= cos 220       [11*pi/9=11 * 20]

cos 220= cos (180+40)

w k t,  cos (180+∅)=    - cos∅

-cos 40°  

this lies in 3rd quadrant.

in 3rd quadrant ,  tan and cot are +ve, while the rest of the trignometric function will be -ve