There is also another formula which is confusing

Make e the subject

T = (1 + e/1 – e) x √L/10

Is that it?

Sorry, I mistyped it there is meant to be a 5 instead of a 10, and the square root is over the whole of L/5

Ok, so;



Multiply by 1-e, on both sides:



Expand both sides:



Bring all the 'e' on one side:





Then factorise e;



It's nearly finished, can you take it now? :)

I hope it helped! :)