What is the amplitude of the graph of f ( x ) = sin ( x + 3 π ) + cos ( x + 6 π ) ?
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This becomes sin ( x + π / 3 ) + sin ( π / 2 − x − π / 6 )
= sin ( x + π / 3 ) + sin ( π / 3 − x )
= 2 sin ( π / 3 ) cos x
The amplitude of the above function is 2 sin ( π / 3 ) = 3
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
How does that help in knowing the amplitude....???!!!
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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.
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