Mathematics 4024 · O Level · Non-right-angled triangles
Non-right-angled triangles — practice question
The diagram indicates the locations of ports $A$ and $B$, together with lighthouse $L$. From $L$, the bearing of $B$ is $062^\circ$. $AB = 13\text{ km}$, $BL = 14\text{ km}$ and $AL = 8\text{ km}$.
(a)[4]
Calculate the bearing from $L$ to $A$.
(b)[2]
A boat is at $C$. $C$ is $11\text{ km}$ from $B$, and $\angle BCA = 90^\circ$. The boat goes straight to port $A$. Find the distance travelled by the boat.
(c)[2]
The boat then moves straight from port $A$ to port $B$. Its average speed is $3.75\text{ km h}^{-1}$. Calculate how long it takes the boat to travel from port $A$ to port $B$. Give your answer in hours and minutes.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “128.03 degrees” …