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## #1 2017-07-22 23:53:33

Oggi
Member
Registered: 2017-07-10
Posts: 2

### Trigonometry

For the questions below, I don't want the answers, I just want guidance on what parts of Trigonometry to study, so I can solve the following by myself

Consider the function y = 2cos(2x + π) for −3π/4 ≤ x ≤ 3π/4
Follow the steps below to sketch the graph of y.
(a) State the amplitude, period and phase shift in the graph of this function.
(b) Solve y = 2cos(2x + π) for −3π/4 ≤ x ≤ 3π/4 to ﬁnd the horizontal intercepts (x-intercepts) of the function.
(c) Find the values of x for 3π/4 ≤ x ≤ 3π/4 for which the maximum and the minimum values of the function occur.
(d) State the range of the function.
(e) Using the information obtained in (a)–(d), draw the graph of y = 2cos(2x + π) for −3π/4 ≤ x ≤ 3π/4

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## #2 2017-07-23 00:31:23

bob bundy
Registered: 2010-06-20
Posts: 8,137

### Re: Trigonometry

hi Oggi

The Maths Is Fun trig pages offer some help and the interactive graphs are brill.  But I cannot find an option for changing x to 2x + pi.

http://www.mathsisfun.com/algebra/trigo … index.html

But there's a way round this.  Look at the function grapher.  You can choose your own function, and scale.

http://www.mathsisfun.com/data/function-grapher-old.php

Hope that helps,

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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## #3 2017-07-23 01:50:17

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,107
Website

### Re: Trigonometry

If you're a bit lost on how to attempt this, then it might be best to first understand what the questions are asking. Suppose instead that the function you were considering was
Would you be able to answer those questions in this case, i.e. find the maxima, minima, range, intercepts, amplitude, period, phase shift and graph the function?

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## #4 2017-07-23 04:59:13

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,838
Website

### Re: Trigonometry

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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