It can be found by using the formula, 
 an = a+(n-1)d
 
        
             
        
        
        
Answer:
Step-by-step explanation:
a/b=4/5    b/c=2/9
Ration of a to c is 
a/c=4/9
 
        
                    
             
        
        
        
The formula is
(theta)/360 · 2(pi)r
theta is the given angle
r is radius of the circle
        
                    
             
        
        
        
Answer:
5:6
20:24
30:36
Step-by-step explanation:
In order to find an equivalent ratio, you have to multiply or divide your numerator and denominator by the same number. 
For example: 
10/12 x 3/3
30/36 = 30:36
10/12 is equivalent to 30:36 
 
        
                    
             
        
        
        
From the given options we can say that the only one that represents the area of the sector is; A = n/360 * πr²
<h3>What is the Area of the Sector?</h3>
In circles, a sector is said to be a part of a circle made of the arc of the circle together with its two radii. This means that it is a portion of the circle formed by a portion of the circumference (arc) and radii of the circle at both endpoints of the arc. 
The formula for Area of a sector is given as;
θ/360 * πr²
where;
θ is the central angle of the sector
r is radius
Now, looking at the given options we can say that the only one that represents the area of the sector is;
A = n/360 * πr²
where n is the central angle of the sector
Read more about Area of Sector at; brainly.com/question/16736105
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