Question

Trig help! Graphs in reply post.

Answer 1

Choose the function whose graph is given by

Answer 2

options : y = 4cos(2x)

y = -4cos(x)

y = 4cos(x)

y = 4cos(x)

Answer 3

I'm in between B and D

Answer 4

@LastDayWork

Answer 5

@kc_kennylau

Answer 6

Just plug 0 and pi/4 in to check :)

Answer 7

where do I plug that in? in each option?

Answer 8

yep :)

Answer 9

oh sorry the options are all messed up

Answer 10

What's the difference between the third option and the fourth option?

Answer 11

@QueenBee232
What's the fundamental period of -
cos(x)
the function in the graph

Answer 12

it's supposed to be y= 4cos(2x)
y = -4cos (pi/2 x)
y = 4cos(1/2 x)
y = 4cos(pi/2 x)

Answer 13

period would be 2pi/ something?

Answer 14

Well, to tackle these problems, you would have to plug values in.

Answer 15

what values?

Answer 16

Tell me separately -
Period of cos(x)
Period of the function in graph

@kc_kennylau
The question can be solved simply by analysis (without any calculations)

Answer 17

ok...

Answer 18

@lastdaywork ok sorry

Answer 19

@kc_kennylau
Never mind :)

Answer 20

so what's the steps?

Answer 21

what do I do?

Answer 22

Tell me separately -
Period of cos(x)
Period of the function in graph

Answer 23

idk

Answer 24

what is it?

Answer 25

Let f(x) be any function; if for any T>0
f(x+t) = f(x) ; for all x in the domain
Then T is called a period of the function.

The smallest positive value of T is called the fundamental period.

Answer 26

As cos(x+2pi) = cos(x) ; for all real x
2pi is the (fundamental) period of cos(x)

Now can you tell me the fundamental period of the function in graph.
Hint: Measure the horizontal length after which the graph repeats itself.

Answer 27

I just see all pi and 2pi and 4 through -4

Answer 28

don't mean to rush but teacher just put a timer on this practice and have 30 minutes left and I have 5 more questions left so..

Answer 29

@LastDayWork

Answer 30

The fundamental period of the graph is pi.
The answer for your question is : y = 4cos(2x)

I dont think I can explain anything while their is a time limit :(

Answer 31

oh well that's ok I can come back later and you could explain to me for this moment just need quick steps and answer

Answer 32

See this - http://www.wolframalpha.com/input/?i=y%3D4cos%282x%29

Answer 33

ok could you help me with a few more?

Answer 34

I am sorry, it is against the Code of Conduct :(

Answer 35

oh I thought it wasn't because that's how I've worked before

Answer 36

could you just check my answers then for the next?

Answer 37

Answer options : y = tan(x - pi) + 2 ; y = tan(x+2) - pi ; y= tan(x+ pi) - 2 ; y = tan(x-pi) -2

Answer 38

If it is against the ethics of your school; then helping you is in violation of the CoC
So tell me what exactly are you doing ?

Answer 39

it's not a violation of any ethics just a practice set

Answer 40

Then no problem..I'll check your answers.

Answer 41

ok!

Answer 42

for the second question my answer is A

Answer 43

is that correct?

Answer 44

options : y = tan(x - pi) + 2 ; y = tan(x+2) - pi ; y= tan(x+ pi) - 2 ; y = tan(x-pi) -2

Answer 45

first option?

Answer 46

Actually the answer is y = tan(x) + 2
As, pi is the fundamental period of tan(x) ; we can write -
y = tan(x-pi) + 2

Answer 47

ohh! I think I understand the answer now :)

Answer 48

ok next question answer options : y = sec(1/2 x) + 2 ; y = 2sec(1/2 x) ; y = 1/2 sec(2x) ; y=2csc(1/2 x)

Answer 49

My answer is D? I know that csc never touches x-axis so that's why I'm guessing it's D. Not sure though

Answer 50

Firstly, the function is closer to sec (reciprocal of cos)

Then its fundamental period became twice (i.e. 4pi) - every x coordinate became twice
so you should substitute x with (1/2)

Finally, it's vertices are at (-2) and 2 ; instead of (-1) and 1 - everything y-coordinate became twice
So you should substitute y with (1/2)y

So the answer becomes
y/2 = sec(x/2)
or
y = 2sec(x/2)

Answer 51

ohh

Answer 52

Question 4. Answer options : 1,2,3, or 4. My guess is 4?

Answer 53

-1 <= cos <= 1

implies
-A <= Acos <= A

Now tell me what's your guess ??

Answer 54

1?

Answer 55

Actually 2
(see the minimum and maximum value of the graph)

Answer 56

oh! I thought it was adding those 2

Answer 57

Answer options : 1,2,3,4 my guess is 3?

Answer 58

Yep, 3 is correct :)

Answer 59

really? awesome!

Answer 60

Not sure on this next one

Answer 61

Like I said before, the maximum value of cos(...) is 1 (and minimum is -1);
Now tell me the answer.

Answer 62

1,-1?

Answer 63

Why two answers ??

Answer 64

oh sorry umm -1?

Answer 65

Actually 1 is the correct answer.
y = -3 + 4*1 = 1

Answer 66

for this question would the answer for maximum be 5?

Answer 67

Answer for maximum is 5; thats correct.
But the question is asking for the minimum value

Answer 68

that's the last question

Answer 69

oh

Answer 70

so what would minimum be?

Answer 71

1? 4?

Answer 72

Can you tell me the minimum value ??

Answer 73

6-5 = 1?

Answer 74

For minimum value; replace cos(...) with (-1)
Now tell me whats your answer.

Answer 75

-7?

Answer 76

alright thank you very much!

Answer 77

Refer to the attachment.