Proving Equations using Euler's Identity

  • Thread starter roldy
  • Start date
  • #1
roldy
237
2
1. Use Euler's identity to prove that cos3(t)=3/4cos(t)+1/4cos(3t)



2. ei[tex]\theta[/tex]=cos(theta)+i*sin(theta)



3. 3/4cos(t)+1/2cos(3t)=3/4((eit+e-it)/2)+1/4((ei3t+e-i3t)/2)
 

Answers and Replies

  • #2
Pengwuino
Gold Member
5,009
17
You might want to go the other route and figure out what [tex]cos(t)^3[/tex] is upon substituting the identity for cos(x).
 
  • #3
roldy
237
2
Got it. Thanks a bunch. That was pretty simple, just overlooked the simple substitution.
 

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