Youre flying from joint base lewis mcchord jblm to an...

You're flying from Joint Base Lewis-McChord (JBLM) to an undisclosed location 397 km south and 240 km east. Mt. Rainier is located approximately 56 km east and 40 km south of JBLM. If you are flying at a constant speed of 800 km/hr, how long after you depart JBLM will you be the closest to Mt. Rainier? In minutes.

Transcript

00:01 So in this problem, we're flying a plane from joint -based lewis mccord.

00:08 So we're up here at j .b .l .m.

00:13 We're going to some undisclosed location.

00:17 And it's this point down here, right? we're flying to this point.

00:23 And it is 397 kilometers south and 240 kilometers.

00:40 East.

00:43 Along the way, mount rainier is over here, just outside our flight path, and it is 40 kilometers south and 56 kilometers east from where we're at.

01:14 And we're going to be cruising at 800 kilometers per hour.

01:21 Okay, and want to know when this distance is the closest or the minimum.

01:35 Well, it's going to be at the minimum when this line through here is perpendicular to our flight path is when that's going to happen.

01:48 So let's write the equation for our flight path.

01:52 Well, if we say that this is where we're starting that's zero, right? then our flat path is y equals minus 397x over 240, right? okay.

02:18 So in other words, 240y equals minus 397x.

02:27 Okay, now then, this perpendicular line then, going through the point at mount rainier, has a negative inverse slope and so it is y minus 40 yeah right y minus y 1 is equal to m times x minus x1 point slope formula and the slope is a negative reciprocal of that so it's 240 over 397 times x minus 56 okay.

03:20 So multiply all this out.

03:25 Then i get 397y is equal to 240x minus 240 and then i'm going to add 40 to it.

04:00 This is supposed to be plus, wasn't it? yeah, because it's minus a minus.

04:05 That should have been plus.

04:06 Okay.

04:07 So then i'm going to subtract 40 from it...

Question

Please give Ace some feedback