Do You Know Your Trig Graphs?

Geometry Level 2

What is the amplitude of the graph of f ( x ) = sin ( x + π 3 ) + cos ( x + π 6 ) ? \Large f(x) = \sin\left(x + \frac{\pi}{3}\right) + \cos\left(x+\frac{\pi}{6}\right)?

3 \sqrt 3 2 \sqrt 2 1 1 2 2

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4 solutions

Angel T. López
Oct 2, 2015

Rohit Sachdeva
Oct 2, 2015

This becomes sin ( x + π / 3 ) + sin ( π / 2 x π / 6 ) \sin(x+\pi/3)+\sin(\pi/2-x-\pi/6)

= sin ( x + π / 3 ) + sin ( π / 3 x ) \sin(x+\pi/3)+\sin(\pi/3-x)

= 2 sin ( π / 3 ) cos x 2\sin(\pi/3) \cos x

The amplitude of the above function is 2 sin ( π / 3 ) = 3 2\sin(\pi/3) = \sqrt{3}

Yoon Ho Seol
Apr 29, 2016

The sum of any 2 sine or cosine wave with the same wavelength acquire maximum or minimum amplitude at their intersection. For instance, 2sin; 0 phase difference; intersect at 0; altitude=2sin(0). Another example, sin+cos; 90 phase difference; intersect at 45 deg; altitude=2sin(45). The problem above has phase difference of 60 degree. Therefore the altitude is 2sin(60/2). So the answer is 2*root(3)/2 = root(3). :)

Wait how 2sin(60/2) equals root(3) it must have been equal to 1

Hitesh Yadav - 11 months, 1 week ago
Popular Power
Apr 6, 2019

Calculate f(0).

How does that help in knowing the amplitude....???!!!

Aaghaz Mahajan - 2 years ago

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It gives the right answer, indeed. But i'm not really sure that it's applicable to all problems of such kind.

Jerry Grey - 5 months, 4 weeks ago

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