C1 Maths!
Guys can someone help with the following question..
From a point A, a boat sails due north for 7km to B. The boat leave point B and moves at a bearing of 100 degrees for 10km until it reaches C. Calculate the distance of C from A.
I keep getting the wrong answer. This is my working out:
SinC/7 = Sin100/10
C= 43.6
Therefore angle B is 180-(100+43.6)
= 36.4
AC/sin36.4 = 10/sin100
AC = 10sin36.4 / sin100
= 6.026 cm
However 6.026 isn't the answer. The answer is 11.2.
Where have I gone wrong??
This was posted from The Student Room's iPhone/iPad App
From a point A, a boat sails due north for 7km to B. The boat leave point B and moves at a bearing of 100 degrees for 10km until it reaches C. Calculate the distance of C from A.
I keep getting the wrong answer. This is my working out:
SinC/7 = Sin100/10
C= 43.6
Therefore angle B is 180-(100+43.6)
= 36.4
AC/sin36.4 = 10/sin100
AC = 10sin36.4 / sin100
= 6.026 cm
However 6.026 isn't the answer. The answer is 11.2.
Where have I gone wrong??
This was posted from The Student Room's iPhone/iPad App
Original post by Taraah
SinC/7 = Sin100/10
C= 43.6
SinC/7 = Sin100/10
C= 43.6
This first statement is not true.
Draw a diagram.. You cannot do this question using the sine rule - you have no pairing angle and lengths.
(edited 11 years ago)
Original post by Taraah
The book tells me to use the cosine rule, but I still get the answer wrong. I've written the question exactly the way its written in the book. I drew a diagram but now I'm really confused
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
You should be able to work out the angle ABC by noting that angles on a straight line add up to give 180 degrees.
Then use the fact that
(edited 11 years ago)
Original post by Taraah
The book tells me to use the cosine rule, but I still get the answer wrong. I've written the question exactly the way its written in the book. I drew a diagram but now I'm really confused
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
If you've drawn the sketch correctly you should have a value for a, b and an angle which (if the ship goes on a bearing of 100 from and the angle of a straight line is 180 what would be the angle inside the triangle?) http://gyazo.com/336ae70eb7cd08fc049fc564ef9c676b
Original post by Secret.
If you've drawn the sketch correctly you should have a value for a, b and an angle which (if the ship goes on a bearing of 100 from and the angle of a straight line is 180 what would be the angle inside the triangle?) http://gyazo.com/336ae70eb7cd08fc049fc564ef9c676b
Hey thank you!! I drew the diagram incorrectly, thanks for helping
i got the right answer now, finally! This was posted from The Student Room's iPhone/iPad App
Original post by Secret.
If you've drawn the sketch correctly you should have a value for a, b and an angle which (if the ship goes on a bearing of 100 from and the angle of a straight line is 180 what would be the angle inside the triangle?) http://gyazo.com/336ae70eb7cd08fc049fc564ef9c676b
Hey is it possible that you can help me with a another question:
A helicopter flies on a bearing of 200 degrees from A to B, where AB= 70km. It then flies on a bearing of 150 degrees from B to C, where C is due south of A. Work out the distance of C from A.
I properly know how to work it out, but I struggle with drawing the sketches.. Can you please tell me how to sketch would look like? Because I know I'm not drawing it right.
This was posted from The Student Room's iPhone/iPad App
Original post by Taraah
Hey is it possible that you can help me with a another question:
A helicopter flies on a bearing of 200 degrees from A to B, where AB= 70km. It then flies on a bearing of 150 degrees from B to C, where C is due south of A. Work out the distance of C from A.
I properly know how to work it out, but I struggle with drawing the sketches.. Can you please tell me how to sketch would look like? Because I know I'm not drawing it right.
This was posted from The Student Room's iPhone/iPad App
A helicopter flies on a bearing of 200 degrees from A to B, where AB= 70km. It then flies on a bearing of 150 degrees from B to C, where C is due south of A. Work out the distance of C from A.
I properly know how to work it out, but I struggle with drawing the sketches.. Can you please tell me how to sketch would look like? Because I know I'm not drawing it right.
This was posted from The Student Room's iPhone/iPad App
Hi, sorry for the late reply, I'm guessing it would look something like: http://gyazo.com/78d9fa8f6386c96686a99cbe70af496d
It also shows that C is due south of A
hope this helps.
(I kept the north lines so you can see how I got the drawing, the angles are not exact and don't have to be just approximate e.g. for 200 I used the north line as the angle of 180 and added approx 020 to it.
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