Answer:
Step-by-step explanation:
sec θ=-2
cos θ=-1/2=-cos π/3
=cos(π-π/3),cos(π+π/3)
=cos 2π/3,cos 4π/3
=cos(2nπ+2π/3),cos(2nπ+4π/3)
=cos(6nπ+2π)/3,cos(6nπ+4π)/3
θ=(6nπ+2π)/3,(6nπ+4π)/3
n=0,1,2
θ=2π/3,4π/3,8π/3,10π/3,14π/3,16π/3
Take first value values.
