00:01
The girl is flying a kite that is 30 meters above her head.
00:05
So let's say this point here is the girl.
00:09
Then the kite is 30 meters above her head, meaning the distance here is 30 meters.
00:17
So the kite is flying horizontally away from the girl.
00:22
So let's say moving this way at 2 meters per second.
00:31
We're looking for the rate at which the string is being let.
00:35
Out.
00:36
Okay, so the string would be connecting the girl to the kite.
00:45
So let's call this horizontal distance here x and let's call this distance here s for strength.
00:54
So we have d x d t is equal to two meters per second and we're looking for d s d t when the string is 70 meters.
01:10
So that means evaluated that s is equal to 70.
01:17
Okay, so this here is a right angle triangle, meaning we can use pythagorean theorem to relate all the numbers here.
01:27
So we have s squared is equal to 30 squared plus x squared.
01:37
Okay, so first let's figure out what s is.
01:42
Sorry, let's figure out what x is when s is 70.
01:46
Okay, so if s is 70, then we get, let's write that here.
01:53
So 70 squared is equal to 30 squared plus x squared...