If period of 

 is one-half the period of 

 and 
<span>

  has a period of 2π, then 

 and 

. 
</span>
To find the period of sine function 

 we use the rule 

.
<span /><span />
f is sine function where f (0)=0, then c=0; with period 

, then 

, because 

. 
To find a we consider the condition 

, from where 

.
If the amplitude of 

 is twice the amplitude of 

 , then 

 has a product factor twice smaller than 

 and while period of 

<span> </span> is 2π and g(0)=0, we can write 

. 
 
        
        
        
Use Pi, 3.14.  Divide the Diameter by 3.14 and you should get your answer.  That's all I know.
 
 
        
        
        
It’s the second option 
sin(45)=13/x
        
             
        
        
        
3.option a (-8,2)
4.option b (5,4)