1. The problem statement, all variables and given/known data A signal E(t) is made up of three terms, each having the same frequency but differing in phase: E(t) = E0cos(ωt) + E0cos(ωt + δ) + E0cos(ωt + 2δ) It is possible to find the amplitude of the sum vector by summing each vector described as a magnitude multiplied by a phase. The sum will therefore contain three terms. You can simplify this to express the sum as a real number times a phase. The real number is the amplitude of the sum vector. Make a plot of the amplitude of the sum vector as a function of δ as δ varies from 0 to 2∏. 2. Relevant equations A signal can be represented as the real part of a complex number z, z = Aei(wt+∅) = A[cos(wt+∅) + jsin(wt+∅)] 3. The attempt at a solution E(t) = E0cos(ωt) + E0cos(ωt + δ) + E0cos(ωt + 2δ) E(t) = E0exp(iωt) + E0exp(i(ωt + δ)) + E0exp(i(ωt + 2δ)) E(t) = E0exp(iωt) * (1 + exp(iδ) + exp(i2δ)) E(t) = E0cos(ωt) * (1 + exp(iδ) + exp(i2δ)) I can't think of a way to simplify it any further to put it in the form real number * a phase term. Am I missing something?