Answer:
B.
Step-by-step explanation:
as for my answer please correct if im wrong
 
        
             
        
        
        
Answer:
Prime numbes
Step-by-step explanation:
Numbers whose only factors are 1 and itself are called prime numbers.
 Such numbers have only two factors.
Examples are: 2, 3, 5, 7 ,9... etc.
 
        
                    
             
        
        
        
Answer:
θ = 2π/3 or 5π/3
Step-by-step explanation:
2 cosθ + 1= 0
when  + 1 goes to R H S Side than it becomes negative by transposition   method
2 cos = -1
now by dividing by 2 both sides we get
cosθ  =  -
since cosθ is negative
Cosθ = - cos 60°
it means either cosθ lies in 2nd or third quadrant 
θ = π - π/3
or
θ = 2π- π/3
so θ = 2π/3 or 5π/3