## ivanzud one year ago Urgent:Action Required::: The temperature of a chemical reaction ranges between 40 degrees Celsius and 180 degrees Celsius. The temperature is at its lowest point when t = 0, and the reaction completes 1 cycle during a 12-hour period. What is a cosine function that models this reaction?

1. ivanzud

help!

2. ivanzud

3. ivanzud

is it f(t) = 70 cos 12t + 110?

4. anonymous

C.

5. CBARREDO1

C

6. ivanzud

why C?

7. anonymous

the amplitude A of your function is: $\Large A = \frac{{180 - 40}}{2} = ...?$

8. ivanzud

70

9. CBARREDO1

Yes

10. anonymous

Corrcet

11. ivanzud

but c has -70

12. anonymous

since the period of our function is 12 hours, so the shape og our function has to be this: $\Large \cos \left( {\frac{{2\pi }}{{12}}t} \right)$

13. ivanzud

but why -70 in the front?

14. anonymous

since at t=0, the value is 40, then we have this drawing: |dw:1436896425801:dw| now, if I set t=0 into the first option I get: f(0)= 180 so the first option is not the right option

15. ivanzud

ok so it is C.

16. CBARREDO1

Yes C

17. anonymous

please substitute t=0 into the third option, what do you get? f(0)=...? -70 cos + 110? we have: $\Large - 70\left( {\cos 0} \right) + 110 = - 70 \times 1 + 110 = 40$ So da answer is C. U WELCOME IF ANY OF YALL NEED HELP IN MATH JUST ASK ME IM A LITTLE GOOD IN MATH k PEACE OUT SON