work on better figures
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@@ -218,35 +218,64 @@ This bounds the expression $\sin(x)/x$ between $1$ and $\cos(x)$ and as $x$ gets
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The above bound comes from this figure, for small $x > 0$:
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::: {#fig-sin-cos-bound}
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```{julia}
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#| hold: true
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#| echo: false
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gr()
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p = plot(x -> sqrt(1 - x^2), 0, 1, legend=false, aspect_ratio=:equal,
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linewidth=3, color=:black)
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θ = π/6
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y,x = sincos(θ)
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col=RGBA(0.0,0.0,1.0, 0.25)
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plot!(range(0,x, length=2), zero, fillrange=u->y/x*u, color=col)
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plot!(range(x, 1, length=50), zero, fillrange = u -> sqrt(1 - u^2), color=col)
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plot!([x,x],[0,y], linestyle=:dash, linewidth=3, color=:black)
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plot!([x,1],[y,0], linestyle=:dot, linewidth=3, color=:black)
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plot!([1,1], [0,y/x], linewidth=3, color=:black)
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plot!([0,1], [0,y/x], linewidth=3, color=:black)
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plot!([0,1], [0,0], linewidth=3, color=:black)
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Δ = 0.05
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annotate!([(0,0+Δ,"A"), (x-Δ,y+Δ/4, "B"), (1+Δ/2,y/x, "C"),
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(1+Δ/2,0+Δ/2,"D")])
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annotate!([(.2*cos(θ/2), 0.2*sin(θ/2), "θ")])
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imgfile = tempname() * ".png"
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savefig(p, imgfile)
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caption = "Triangle ``ABD`` has less area than the shaded wedge, which has less area than triangle ``ACD``. Their respective areas are ``(1/2)\\sin(\\theta)``, ``(1/2)\\theta``, and ``(1/2)\\tan(\\theta)``. The inequality used to show ``\\sin(x)/x`` is bounded below by ``\\cos(x)`` and above by ``1`` comes from a division by ``(1/2) \\sin(x)`` and taking reciprocals.
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"
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plotly()
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ImageFile(imgfile, caption)
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plt = let
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gr()
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empty_style = (xaxis=([], false),
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yaxis=([], false),
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framestyle=:origin,
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legend=false)
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axis_style = (arrow=true, side=:head, line=(:gray, 1))
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text_style = (10,)
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fn_style = (;line=(:black, 3))
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fn2_style = (;line=(:red, 4))
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mark_style = (;line=(:gray, 1, :dot))
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domain_style = (;fill=(:orange, 0.35), line=nothing)
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range_style = (; fill=(:blue, 0.35), line=nothing)
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plot(; empty_style..., aspect_ratio=:equal)
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plot!(x -> sqrt(1 - x^2), 0, 1; line=(:black, 2))
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θ = π/6
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y,x = sincos(θ)
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col=RGBA(0.0,0.0,1.0, 0.25)
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plot!(range(0,x, length=2), zero, fillrange=u->y/x*u, color=col)
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plot!(range(x, 1, length=50), zero, fillrange = u -> sqrt(1 - u^2), color=col)
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plot!([x,x],[0,y], line=(:dash, 2, :black))
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plot!([x,1],[y,0], line=(:dot, 2, :black))
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plot!([1,1], [0,y/x], line=(2, :black))
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plot!([0,1], [0,y/x], line=(2, :black))
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plot!([0,1], [0,0], line=(2, :black))
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Δ = 0.05
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annotate!([(0,0+Δ, text(L"A", 10)),
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(x-Δ,y+Δ/4, text(L"B",10)),
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(1+Δ/2,y/x, text(L"C", 10)),
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(1+Δ/2,0+Δ/2, text(L"D", 10)),
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(0.2*cos(θ/2), 0.2*sin(θ/2), text(L"\theta", 12))
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])
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current()
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end
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plt
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```
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```{julia}
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#| echo: false
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plotly()
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nothing
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```
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Triangle $\triangle ABD$ has less area than the shaded wedge, which has less area than triangle $\triangle ACD$. Their respective areas are $(1/2)\sin(\theta)$, $(1/2)\theta$, and $(1/2)\tan(\theta)$. The inequality used to show $\sin(x)/x$ is bounded below by $\cos(x)$ and above by $1$ comes from a division by $(1/2) \sin(x)$ and taking reciprocals.
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:::
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To discuss the case of $(1+x)^{1/x}$ it proved convenient to assume $x = 1/m$ for integer values of $m$. At the time of Cauchy, log tables were available to identify the approximate value of the limit. Cauchy computed the following value from logarithm tables:
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