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# Trigonometry watch

1. Hi!

I have the following question which I have failed to solve:

Three towns A, B and C lie on a straight road running east from A. B is 6 km from A and C is 22 km from A. Another town D lies to the north of this road and it lies 10 km from both B abd C. Calculate the distance of D from A and the bearing of D from A.
2. (Original post by salem)
Hi!

I have the following question which I have failed to solve:

Three towns A, B and C lie on a straight road running east from A. B is 6 km from A and C is 22 km from A. Another town D lies to the north of this road and it lies 10 km from both B abd C. Calculate the distance of D from A and the bearing of D from A.
Just draw a picture and you find:

I am not sure what you mean by bearing.
3. (Original post by way2go)
Just draw a picture and you find:

I am not sure what you mean by bearing.
bearing is the angle from north.
4. (Original post by salem)
Hi!

I have the following question which I have failed to solve:

Three towns A, B and C lie on a straight road running east from A. B is 6 km from A and C is 22 km from A. Another town D lies to the north of this road and it lies 10 km from both B abd C. Calculate the distance of D from A and the bearing of D from A.
try using pythagaros' theourum instead of trig...

G
5. (Original post by salem)
Hi!

I have the following question which I have failed to solve:

Three towns A, B and C lie on a straight road running east from A. B is 6 km from A and C is 22 km from A. Another town D lies to the north of this road and it lies 10 km from both B abd C. Calculate the distance of D from A and the bearing of D from A.

Sorry not to spoonfeed you but have you tried drawing a little sketch? Here are a couple of hints:

Triangle BCD is isosceles.
Make sure you know the cosine rule.

J.
6. (Original post by salem)
Hi!

I have the following question which I have failed to solve:

Three towns A, B and C lie on a straight road running east from A. B is 6 km from A and C is 22 km from A. Another town D lies to the north of this road and it lies 10 km from both B abd C. Calculate the distance of D from A and the bearing of D from A.
First thing to do is construct a diagram of the problem.

A, B and C should be on a straight line. Since D is the same distance from B and C this should tell you that BCD is an isosceles triangle. It will also be helpful to split this triangle down the middle so you get a right angled triangle. You can then use Pythagoras' theorem to find the length of AD. From this, you can get the bearing.

Good luck

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