how can we write (A1+A2cosphi)=Rcostheta and A2sinphi=Rsintheta. there should be a relation between(A1+A2cosphi) and A2sinphi ?
9 years ago
by
sudeep khare
Ans
1
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In both equations these are constant values A1, A2 and phi and we are expressing these constants in terms of other constants R and theta... relation among constant is also calculated further in the video...
9 years ago
by
Physics Galaxy
Ans
2
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I found to easier to think of it as working backwards:
Let R be defined as R = sqrt(A1^2 A2^2 2A1A2cos(phi)).
Now since (A1 A2cos(phi))^2 (A2sin(phi)^2) = R^2,
we can now write that (A1 A2cos(phi)) = Rcos(theta) and A2sin(phi) = Rsin(theta)
where tan(theta) = A2sin(phi)/(A1 A2cos(phi))
We could also have written that (A1 A2cos(phi)) = Rsin(beta) and A2sin(phi) = Rcos(beta), but by convention, cos is used for the former and sin for the latter.
Writing it this way makes the final expression easier to remember and less congested.
6 years ago
by
Kishore Sathia
Ans
3
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*A1^2 plus A2^2 plus 2A1A2cos(phi)
6 years ago
by
Kishore Sathia