<PRE><B>Question 972065</B>
A plane is heading north-west at 480km/h and is in contact with another plane which leaves the same airport at the same time and heads north-east at 400km/h.
 How far apart are the planes (to the nearest km) after 90 minutes?
:
Change 90 min to 1.5 hrs
Find the distance each traveled in that time
480 * 1.5 = 720 km
400 * 1.5 = 600 km
The angle between the paths of the two aircraft is 90 degrees, so we can use:
a^2 + b^2 = c^2, where
a = 720
b = 600
c = distance between the two aircraft after 90 min
therefore:
c = {{{sqrt(720^2 + 600^2)}}}
c = 937 km</PRE>