# Proving Equations using Euler's Identity

1. Use Euler's identity to prove that cos3(t)=3/4cos(t)+1/4cos(3t)

2. ei$$\theta$$=cos(theta)+i*sin(theta)

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

You might want to go the other route and figure out what $$cos(t)^3$$ is upon substituting the identity for cos(x).