00:01
In this problem, we've been given this co -sequent function, 200 ,000 co -seacant of pi over 42 times x.
00:08
We know that we're looking at the interval of x from 0 to 42, and we are told that this function g of x is giving us the distance between earth and an approaching comet over these 42 days.
00:24
So when we find g of 7, what we're doing is we're finding the distance between the earth and the comet, after seven days.
00:33
So let's plug this in and let's see what we can get.
00:35
We have 200 ,000 times the co -secant of pi over 42 times seven.
00:48
So this is going to end up being two times the co -secant of seven pi over 42, which reduces to pi over six.
01:10
All right, so we need to go back to our unit circle and we need to think about how co -seant is related to the other trick functions that we do know.
01:19
We know that co -sequent is the reciprocal of sign.
01:22
So this is really 200 ,000 times 1 over the sign of pi over 6.
01:29
And we know that pi over 6, if you think in degrees, is 30 degrees.
01:35
P pi over 6 is 30 degrees.
01:37
Sign is the x value on the unit circle at pi over 6.
01:41
So that's going to come out to be one half.
01:45
So this is 200 ,000 times 1 over 1 half, which is just 200 ,000 times 2.
01:58
So this comes out to be 400 ,000.
02:00
So the distance is 400 ,000 kilometers at seven days.
02:07
Then we want to know what is the minimum distance, what is the closest this gets to earth? and for this, we need to remember, let's remember what cosecican looks like.
02:17
Co -secant is going to be the reciprocal of sign.
02:20
So if we have sign at looking like this, it's going to be a value of 1 and a value of negative 1 here, and it oscillates between this, i missed my point...