## BloomLocke367 one year ago Law of cosines

1. BloomLocke367

|dw:1432929186134:dw| I'm looking for angle A.

2. BloomLocke367

@IrishBoy123

3. IrishBoy123

|dw:1432929324519:dw| OK :p

4. BloomLocke367

that's confusing

5. BloomLocke367

i'm confused

6. IrishBoy123

@BloomLocke367 for law of cosines, think Pythagoreas Theorem with added power if you want to understand it, that's where to start. if you just want the answer, there will be no limit to the amount of online calculators that will do the work for you. otherwise, you have to walk the long mile.

7. IrishBoy123

|dw:1432930383845:dw|

8. BloomLocke367

so what exactly do I do with that?

9. IrishBoy123

to solve $a^2 = b^2 + c^2 - 2 \ b \ c \ \cos A$ calculate $a^2 ,\ b^2, \ c^2 \ and \ 2 bc$ you have all the data cos(A) follows from that

10. BloomLocke367

so I have289=484+900-1320cosA

11. BloomLocke367

@IrishBoy123

12. IrishBoy123

awesome

13. IrishBoy123

i agree

14. BloomLocke367

now what do I do?

15. IrishBoy123

$1320 \ cosA = 484 + 900 - 289 ;\ \ \ cosA = \frac{484 + 900 - 289}{1320}$

16. IrishBoy123

cos A = ?? if it's not 33.948, you can sack me.

17. BloomLocke367

I got 0.829...

18. IrishBoy123

good because if cos A = 0.829..., then A = 33.948 [degrees]

19. BloomLocke367

how so?

20. IrishBoy123
21. BloomLocke367

Can you help with some more?

22. IrishBoy123

@BloomLocke367 gotta go well done, you can do this stuff easily ciao!