## anonymous one year ago help please

1. anonymous

what exactly?

2. anonymous

3. anonymous

Do you know 30-60-90 triangle rule?

4. anonymous

no

5. anonymous

best way is to use law of cosines

6. anonymous

c^2 = a^2 + b^2 - 2ab cos C

7. anonymous

plug in 60 for cos(c) (so basically cos(60)) and plug in 3 and 4 for a and b respectively

8. anonymous

$c^2=1^2+4^2-2\times 3 \times 4 \times \cos (60)$

9. anonymous

so replace that 1^2 with 3^2