Homework Help

What is the right choice for question 21) ? http://postimg.org/image/p07cc10w7/

user profile pic

jayson94 | Salutatorian

Posted August 19, 2013 at 2:02 AM via web

dislike 1 like

What is the right choice for question 21) ?

http://postimg.org/image/p07cc10w7/

1 Answer | Add Yours

user profile pic

embizze | High School Teacher | (Level 1) Educator Emeritus

Posted August 19, 2013 at 2:50 AM (Answer #1)

dislike 0 like

From the graph we see that tha max=3, min=-1, period is `pi` , and there is no horizontal shift (phase shift.) (We know there is no phase shift since the graph starts at the maximum at x=0 as does the cos function.)

The equation is `y=acos(b(x-h))+k` :

a: a is the amplitude `a=("max"-"min")/2=(3-(-1))/2=2`

positive as the graph is not inverted.

b: `b=(2pi)/p` where p is the period so b=2

h: h=0 as there is no phase shift

k: k is the midline `k=("max"+"min")/2=(3+(-1))/2=1`

The equation is y=2cos(2x)+1.

The answer is (a)

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes