## anonymous 4 years ago Find the length of a if the measure of angle A equals 62 degrees b = 15, and c = 21.

1. anonymous

|dw:1338954330473:dw|

2. anonymous

Do you know if one of the angles are 90 degrees? I mean in the problem, not in the picture i just drew.

3. anonymous

Idts

4. anonymous

i seen this prob before

5. anonymous

ok then i'm not sure. Because you can use sin, cos, tan only when it's a right triangle. sorry :(

6. anonymous

It's okay!

7. anonymous

|dw:1338954774600:dw|

8. anonymous

do you know the law of cosines?

9. AravindG

ya use law of cosines

10. anonymous

Yes, it's Law of Cosines problem

11. anonymous

use law of sine here

12. anonymous

a^2 = 21^2 + 15^2 - 2*21*15cosA

13. AravindG

$\huge \cos A =\frac{b^2+c^2-a^2}{2bc}$

14. anonymous

Ok!

15. AravindG

:)

16. AravindG

no rewards?

17. anonymous

Everyone gets one!

18. AravindG

bt i didnt get any medals :(