## briana.img one year ago FInd the measure of angle C

1. briana.img

I've tried it twice and the second time i got 12.51400

2. briana.img

I have fone $a^2=13^2+17^2-2(13)(17)\cos47$

3. briana.img

done*

4. anonymous

For this one, use the sine law. Do you know it?

5. briana.img

@ospreytriple yeah hold on let me try it out

6. briana.img

@ospreytriple 10sinB=17sin47???

7. anonymous

Shouldn't it be 13, not 10?

8. briana.img

@ospreytriple oh yeah sorry about that 13sinb=17sin4

9. anonymous

OK. The way I'm used to using the sine law is as follows:$\frac{ \sin \left( A \right) }{ a } =\frac{ \sin \left( B \right) }{ b }$. Is this the way you have it?

10. briana.img

@ospreytriple yeah i did that but you have to rearange to the way i had it and then do s$sinb=\frac{ 17\sin47 }{ 13 }$

11. anonymous

I think there's an error in the rearranging. You have $\frac{ \sin \left( B \right) }{ b }=\frac{ \sin \left( C \right) }{ c }$To isolate sin(C) you would multiply both sides of the equation by c, giving$\frac{ c \sin \left( B \right) }{ b }=\sin \left( C \right)$Make sense?

12. briana.img

@ospreytriple yeah

13. anonymous

OK. So solve$\sin \left( C \right)=\frac{ 17 \sin \left( 47 \right) }{ 13 }$

14. briana.img

@ospreytriple calculator got 1.27436702

15. anonymous

What do you get for sin(47)?

16. briana.img

@ospreytriple 0.7313

17. anonymous

Good. Multiply that number by 17 and divide that answer by 13. What do you get?

18. briana.img

@ospreytriple 0.956315

19. anonymous

Excellent. Now evaluate $C=\sin ^{-1}\left( 0.956315 \right)$

20. briana.img

@ospreytriple calculator is getting 73.00200763 but doesnt seem right at all

21. anonymous

That's what I get. Is that one of your choices?

22. briana.img

@ospreytriple oh nvm it is i was looking at the wrong problem lmao thank you!!

23. anonymous

Yayyy! Just remember to be very careful how you use your calculator.