@prefix : <http://example.org/arc/euler#>.
@prefix math: <http://www.w3.org/2000/10/swap/math#>.

:answer :text "e^{iπ} + 1 = 0".
:answer :pair (0 0).
:reason :says "Use e^{iθ} = (cos θ, sin θ); with θ = π we get (-1,0), so e^{iπ}+1=0.".
:reason :uses math:cos.
:reason :uses math:sin.
:reason :at 3.141592653589793 .
:reason :cos -1.0 .
:reason :sin 1.2246467991473532e-16 .
:check1 :ok true.
:check2 :ok true.
:check3 :ok true.
:check4 :ok true.
:check5 :ok true.
