# complicated question from a past paper that i dont understand

• Jun 3rd 2009, 05:05 AM
emmalou264
complicated question from a past paper that i dont understand
An aeroplane flies at a constant spead of 800 kph in a straight line from
(-100,-200) to (300,1000)

x axis and y axis are east and due north

1) find the equation of the straight line.

I got y= 3x +100

2) find the direction of travel of the aeroplane as a bearing, with the angle correct to one decimal place.

i HAVE NO IDEA

3) There is a beacon at (0, 200) which has a range of 100km
Find equation of straight line

I know equation is (x-a)^2 + (y-b)^2 = r^2

4) find the points of intersection of the straight line and the circle, hence find the time during which the aeroplane is within range of the radar station in minutes to one decimal place.

HELP???

Thanks
• Jun 3rd 2009, 05:17 AM
masters
Quote:

Originally Posted by emmalou264
An aeroplane flies at a constant spead of 800 kph in a straight line from
(-100,-200) to (300,1000)

x axis and y axis are east and due north

1) find the equation of the straight line.

I got y= 3x +100

2) find the direction of travel of the aeroplane as a bearing, with the angle correct to one decimal place.

i HAVE NO IDEA

The line has a slope of 3.

Arctan (3) tells us that the line makes an angle of 71.6 degrees with the x-axis or East-West axis.

The complement to this is the angle the line makes with the y-axis or North-South axis.

This would be a bearing of 18.4 degrees NNE.