# Thread: 2 Sin/ Cos Probelms

1. ## 2 Sin/ Cos Probelms

1. y=-9cosx+5

Amplitude:?
Period:?
Phase Shift:?
Range:?

2.-15sin[5(x+(pi/3))]+3

Amplitude:?
Period:?
Phase Shift:?
Range:?

Thanks

1.
Amplitude: 9
Period: 2pi
Phase Shift: 0
Range: [-4,14]

2.
Amplitude:15
Period: (2pi/5)
Phase Shift: (-pi/3)
Range: [-12,18]

2. Originally Posted by qbkr21
1. y=-9cosx+5

Amplitude:?
Period:?
Phase Shift:?
Range:?
Amplitutde is 9 even though the number in front is -9, you take absolute value.

The period is $\displaystyle \frac{2\pi}{|1|}=2\pi$

There is no phase shift.

The minimum value occurs when, $\displaystyle \cos x=1$, thus, -9(1)+5=-4
The maximum value occurs when $\displaystyle \cos x=-1$ thus, -9(-1)+5=14
The range is,
$\displaystyle -4\leq y\leq 14$

Similar idea for each one.

3. ## Re:

Ok so my answer were correct?

4. Originally Posted by qbkr21
Ok so my answer were correct?
Everything's fine except for the phase shift in the second problem. What happened to the 5 in the function?

-Dan