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Yeah good luck man, if you want to use the trig you need a calculator.
sine rule = a/sina = b/sinb = c/sinc
cosine rule = a2=b2+c2 -2bc(cosa) (a2 = a squared)

I have worked some blades like this recently. I had to correct the spine at the place where I removed width from the blade, I did this by laying the blade on a flat surface and removing metal from...