Trig equation

Albi

Junior Member
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May 9, 2020
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cos(3x-π/4)=sin(x)
Can someone help me solve this equation?
 
cos(3x-π/4)=sin(x)
Can someone help me solve this equation?
Use the identity:

sin[x]=cos[(4n+1)π2  x]\displaystyle sin[x] = cos[(4n+1)\frac{\pi}{2} \ - \ x]

Please show us what you have tried and exactly where you are stuck.

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cos(3x-π/4)=sin(x)
Can someone help me solve this equation?
I would probably start with the cofunction identity, replacing sin(x) with cos(pi/2 - x). Then you have two equal cosines, and can consider the two conditions under which the cosines of angles can be equal: either they are coterminal, or one is coterminal with the negative of the other.
 
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