00:01
Alright, so we have to calculate the length travelled by a kite, okay, and the function or the path which the kite will be followed was given as by this function, that is f of x is equals to 150 minus x minus 50 whole square divided by 40, okay? well x will be from 0 to 80 that means we have to find out the length of the path followed by the kite from x is 0 to 80 okay so for that first let's differentiate this curve so f -dice of x we'll be getting as so the differentiation of this will be actually 0 and differentiation of this will be minus 2 by 40 into x minus 50 okay to simplify it so we'll be getting as so the differentiation of this will be getting a difference 0.
00:59
1 by 20 so essentially it will be minus 1 by 20 into x minus 50 so that is the first derivative so let's calculate the length traveled by the height okay so l will be integration 0 to 80 okay root over 1 plus first derivative 1 square so first derivative is this whole square of that will be essentially x minus 50 whole square divided by 20 whole square into d of x.
01:37
Okay, so we have to integrate this function and calculate the total length travel by the kind.
01:42
So for that you have to do substitution.
01:44
So let u as equals to 1 by 20 into x minus 50.
01:59
Okay, so this is u.
02:00
So d you will become, du will become essentially differentiation of x will be 1.
02:08
So d will become d x divided by 20 okay so let's put these values so l will be essentially we'll change the limits as well so if you put the x is equals to zero the lower limit here so zero minus 50 so it will be minus 50 by 20 so the lower limit will change to minus 5 and for upper limit you have to put x is equal to 80 so put 80 minus 50 will be 30 so 30 by 20 will be 3 by 2 okay and the value here we are going to write it down as essentially this will be you assume this quantity as u so the integral will become 1 by u square and d u will be equal to d x by 20 so we can write it down as d x by okay so we have to integrate this so l will be essentially so the integration of this we can write it down as integration of okay, sorry, that's a mistake we have done actually.
03:23
So it should be actually 20 because the value of dx will be 20 d...