## anonymous one year ago Bruce had an EKG to measure his heartbeat rate. After conversion, the function produced could be modeled by a cosine function, and the wave produced a maximum of 4, minimum of −2, and period of pi over 2. Which of the following functions could represent Bruce's EKG read-out?

1. anonymous

f(x) = 4 cos pi over 2x − 2 f(x) = 3 cos 4x + 1 f(x) = 3 cos pi over 2x + 1 f(x) = 4 cos 4x − 2

2. anonymous

f(x) = A cos (Bx + C) + D A = amplitude = ½|max - min| B = (2π)/period C = phase shift = 0 for this problem D = vertical shift = max - amplitude

3. anonymous

A and D are wrong right?

4. anonymous

yes

5. anonymous

i think its C

6. anonymous

The coefficient of x is 2pi/period, so it should be $2 \pi \div \frac{ \pi }{ 2 }$

7. anonymous

oh so its 4

8. anonymous

so 4x

9. anonymous

yep

10. anonymous

i see now its B thank you very much

11. anonymous

you're welcome