Geometry Challenge

[Albert Chan]

(01-13-2024 09:49 PM)Thomas Klemm Wrote:  

(01-13-2024 02:00 PM)Albert Chan Wrote:  … = cis(10) * (1 - cis(60) = 1 + cis(-120) = cis(-60)) = …

You lost me somewhere between here and the missing opening parenthesis.

Sorry about the shorthand (to make above clearer, I added matching parenthesis in red)

cis(10) - cis(70)
= cis(10) * (1 - cis(60))
= cis(10) * (1 + cis(-120)) 
= cis(10) * cis(-60)
= cis(10 - 60)
= cis(-50)