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#1




addition of phasors
hey minor problem, i have two phasors i need to add:
44.7cos(ωt161°) + 126.5(ωt + 63°) how do i add them when one is a cos and the other is a sin, the answer is supposed to be given as a sin, but i cant find anything similar in my notes. the answer is 100sin(ωt +45°). all i need to know is how to write the equation with cos in it as a sine. thanks for any help, i have an exam on monday so help is much appreciated. andy 
#2




Use identities such as ...
cos(a+b)=cos(a).cos(b)sin(a).sin(b) sin(a+b)=sin(a).cos(b)+cos(a).sin(b) to expand your given relationship and then collect like terms  in sin(ωt) and cos(ωt) You end up with something like f(t)=A.cos(ωt)+B.sin(ωt) From this you want f(t)=C.sin(ωt+θ) [f(t)=C.sin(ωt).cos(θ) +C.cos(ωt).sin(θ)] where C=√(A^2+B^2) and θ=arctan(A/B) 
#3




Quote:
i.e. sin(x) = cos(xpi/2) and cos(x)=sin(x+pi/2) 
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addition, phasors 
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