To solve the trigonometric expression we proceed as follows; 7(tan x)^3-21tanx=0 this can be written as: 7(tan x)^3=21tanx dividing through by 7 we get: (tan x)^3=tan x dividing through by tan x we get: (tanx)^1=1 hence; tan x=+\-1 when tan x=1 x=45 when tan x=-1 x=-45 Given that our answer should be at the interval [0,2π] the answer: 45=45/180=1/4π
