Posted by **Rachael** on Thursday, December 30, 2010 at 6:11pm.

A helicopter is 400 miles directly north of Ghana and is flying at 20 miles per hour. A second helicopter is 300 miles east of Ghana and is flying west at 15 mph. What is the rate of change of the distance between the helicopters?

- math -
**Reiny**, Thursday, December 30, 2010 at 6:23pm
You don't say which way the first helicopter is flying, north or south or ...

I will assume it is flying south.

Make a right-angled triangle with y as the remaining distance to Ghana and x as the remaining distance.

let d be the distance between them

d^2 = y^2 + x^2

2d dd/dt = 2ydy/dt + 2xdx/dt

when x=300 and y = 400

d^2 = 300^2 + 400^2

d = 500 (did you recognize the 3,4, 5 triangle ?)

dd/dt = (400(-20) + 300(-15))/(2(500)) = 12.5

## Answer This Question

## Related Questions

- math - Helicopter A is flying due north toward a landing point 10 miles away. ...
- Math Pythagorean - A hiker goes 3 miles north, 2 miles east, one mile south, 4 ...
- calculus - An airplane flying west at 300 miles per hour goes over the control ...
- middle school - Two news helicopters are flying in the same altitude on the way ...
- math - Two helicopters leave Springfield, IL at the same time. One travles north...
- Algebra 2 - A commercial freight carrier is flying at a constant speed of 400 mi...
- Trigonometry- Help! - After one hour in flight, an airplane is located 200 miles...
- math - 13. If two planes leave the same airport at 1:00 PM, how many miles apart...
- Algebra - A coast guard helicopter receives a distress signal from a boat. the ...
- math - Oregon is about 400 miles from west to east, and 300 miles from north to ...

More Related Questions