Year 12s: what will be the first way you research your future options? >>

Addition of waveforms

lazyjimmy

Attachment not found

i have answered below:
edexcel sending.jpg

now it asks:
edexcel sending.jpg

please can someone show me another method?ii

(edited 8 years ago)

Original post by lazyjimmy

Attachment not found

i have answered below:
edexcel sending.jpg

now it asks:
edexcel sending.jpg

please can someone show me another method?ii

I personally cannot thin of another sensible way ...
Maybe some complex number method, with exponentials

Reply 2

mattismad

You do it the very shorthand method, it works but you do not see the underlying mathematics that laces your shorthand method together.

RCos(x+alpha) using Double Angle Formula = R[cosacosx-sinacosx]
Expand it out: Rcosacosx - Rsinacosx
Equate each part and bam.

Is this what you meant?

Reply 3

38_Super

You can use a Phasor diagram (using the fact that a cos curve is the same as a sine curve out of phase by 90 degrees) either graphically or algebraically.

Alternatively you can do it using complex numbers of the form : acosθ + bisinθ but I haven't got my head round that method yet.

The calculations of the answer seem to be identical whichever way you use,