## anonymous one year ago I got an answer for this trig problem and I want to see if it is correct

1. anonymous

2. anonymous

I know the answer is either approximately 50.3m or approximately 39.3m, but I do not know which one it is

3. anonymous

@jim_thompson5910

4. IrishBoy123

did you draw the picture? rough sketch will suffice

5. anonymous

i did

6. IrishBoy123

|dw:1438642173189:dw|

7. anonymous

|dw:1438642164202:dw|

8. anonymous

Here is what I did

9. anonymous

@mathstudent55

10. anonymous

@IrishBoy123 did I solve the problem correctly

11. IrishBoy123

why did you not use cos 43 ?

12. IrishBoy123
13. anonymous

wait why would it be cos 43

14. IrishBoy123

15. anonymous

I guess that it is right I think

16. amistre64

law of cosine is fine, but i dont know how to read the bearings ...

17. IrishBoy123

|dw:1438642650401:dw|

18. anonymous

So my new equation is $d=\sqrt{30^2+34^2-2(30)(24)(\cos(43}))$

19. IrishBoy123

yes but that has to make sense to you.... again http://mathworld.wolfram.com/LawofCosines.html

20. IrishBoy123

and typo (!) : $$34^2 -> 24^2$$

21. anonymous

Your graph made better sense than the link, thank you though, therefore my new anser should be, 20.6m

22. IrishBoy123

if **you** are happy with it in the attached diagram we can say - from Law of Cosines - that $$\large a^2 = b^2 + c^2 - 2 b c\ cos A$$ |dw:1438643019135:dw|

23. anonymous

ok so is my new anser 20.6m

24. IrishBoy123

|dw:1438643119009:dw| and $$b^2 = a^2 + c^2 - 2ac \ cos B$$

25. IrishBoy123

it is Pythagoreas expanded |dw:1438643242132:dw| so $$\large c^2 = a^2 + b^2 - 2ab \ cos C$$

26. anonymous

ok, but can you confirm that I have the right answer

27. IrishBoy123

and yes i seem to agree with you

28. anonymous

ok so the answer to my original problem is20.6

29. IrishBoy123

i should think so

30. IrishBoy123

|dw:1438643502160:dw| look at this, where C = 90 $$c^2 = a^2 + b^2 - 2ab \ cos C = a^2 + b^2 - 2ab \ (0)$$ $$c^2 = a^2 + b^2$$

31. anonymous

Can you help me with a simpler problem that I also dont know whether I got right or wrong

32. anonymous

@jdoe0001

33. jdoe0001

repost anew, thus more eyes :)

34. jdoe0001

20.6 is correct btw

35. anonymous

ok