You didn't include the formula.
Given that there is no data about the mass, I will suppose that the formula is that of the simple pendulum (which is only valid if the mass is negligible).
Any way my idea is to teach you how to use the formula and you can apply the procedure to the real formula that the problem incorporates.
Simple pendulum formula:
Period = 2π √(L/g) 
Square both sides
Period^2 = (2π)^2 L/g
L = [Period / 2π)^2 * g
Period = 3.1 s
2π ≈ 6.28
g ≈ 10 m/s^2
L = [3.1s/6.28]^2 * 10m/s^2 =2.43 m
I  hope this helps you. 
        
             
        
        
        
Answer:
59 degrees, 44 plus 77 is 121, subtract from 180 
 
        
             
        
        
        
Answer:
Stephen: £36
Nick: £36
Brian: £18
Step-by-step explanation:
2+2+1= 5
90/5= 18
18x2= 36
18x2=36
18x1=18
Hope it helps
 
        
             
        
        
        
Answer:
you cant round that to 30 
Step-by-step explanation
29.20
29.2 2 is less than 5 
so you cant round you can only round if the .tens place is 5 or more
 
        
             
        
        
        

Setting 

, you have 

. Then the integral becomes




Now, 

 in general. But since we want our substitution 

 to be invertible, we are tacitly assuming that we're working over a restricted domain. In particular, this means 

, which implies that 

, or equivalently that 

. Over this domain, 

, so 

.
Long story short, this allows us to go from

to


Computing the remaining integral isn't difficult. Expand the numerator with the Pythagorean identity to get

Then integrate term-by-term to get


Now undo the substitution to get the antiderivative back in terms of 

.

and using basic trigonometric properties (e.g. Pythagorean theorem) this reduces to