1. ## bearings, triginometry

A helicopter flies on a bearing of 200° from A to B, where AB=70 km. It then flies on a bearing of 150° from B to C, where C is due south of A. Work out the distance of C from A.

can someone please tell me what is wrong with the diagram I have drawn?

2. The helicopter moves from A to B on a bearing of 200, so the point B should actually be on the other side of A as 200>180.You should end up with a triangle with C directly below A, where AB=70km. you then need to work out angles ABC and BCA so you can use the sine rule to find the length of AC.

3. Hello, Tweety!

A helicopter flies on a bearing of 200° from $\displaystyle A$ to $\displaystyle B$, where $\displaystyle AB = 70$ km.
It then flies on a bearing of 150° from $\displaystyle B$ to $\displaystyle C$, where $\displaystyle C$ is due south of $\displaystyle A$.

Find the distance from $\displaystyle C$ to $\displaystyle A.$
The first leg of the flight looks like this:
Code:
            :
:
:
A *
/  200°
70 /
/
/
/
B *

The second leg looks like this:
Code:
      :
:
B * 150°
:\
: \
:  \
\
\
* C

So the diagram should look like this:
Code:
      :           * A
:         * |
:   70  *20°|
:     *     |
:20°*       |
: *         |
B * 130°      |
: *         |
:30°*       |
:     *     |
:       *30°|
:         * |
:           * C

4. Originally Posted by Tweety
can someone please tell me what is wrong with the diagram I have drawn?
Hi Tweety,

See diagram. And see Soroban's post for the angles.