00:04
Now here we have mr.
00:06
Kelly and mr.
00:08
Sullivan, right? now, these two are riding backs on two different streets, right? so suppose you have a street here and you're another street here, and these two streets at right angles and across the intersection, right, the cross is here.
00:20
And they are approaching the same intersection, approaching this intersection, right? so suppose kelly is approaching here, right? this is kelly.
00:28
Now, kelly is 1 to 50 meters away from across, over from the section at the moment, and is approaching at 450 meter per second, not per minute actually, okay, approaching the intersection.
00:45
And the other one, i mean the mr.
00:48
Civilian actually is 200 meters away from the intersection and his proportion this way at speed, which is 600, 600 meter per minute, okay? so you ask, how, i mean, you asked basically how this distance is changing, right? so let me show it better, how this distance, which is s, right, as a function of t, how this distance would actually change, right? and how fast would this distance change, right? so you see that, suppose this is x and this is y, and the s is given by square of x squared plus y squared, right? and if you take the derivative of s, that's given by x over, actually x plus y, over square, of x plus y, okay? and xx dot, extra plus y, y, dot.
01:39
I forgot this dot.
01:40
X dot of course, according to the question is, you know, 4, 150, and y dot, of course, is 600, right? so this is going to be given by x according to the question is 150, right? and x dot, actually, is 450, and plus y in this question is 200 and times of y dot, which is 600, and divided, of course, by a school of this squared, i forgot.
02:04
X is 150 squared and plus 200 squared, right? so that would be what you found...