\begin{tikzpicture}[scale=0.5]

\tkzInit[xmin=-1,ymin=-3,xmax=5,ymax=3]
\tkzClip

% Draw eye
\path  (-0.5, 0.0) coordinate (E0)
      +( 0.5, 0.5) coordinate (E1)
      +( 0.5,-0.5) coordinate (E2)
       (-0.08,0.0) coordinate (EP)
\tkzSegment(E0/E1)
\tkzSegment(E0/E2)
\tkzMarkAngle[size=.5](E1/E0/E2)

% Draw frustum
\path  (0.0, 0.0) coordinate (F0)
      +(2.0, 1.0) coordinate (F1)
      +(2.0, 0.333) coordinate (F2)
      +(2.0,-0.333) coordinate (F3)
      +(2.0,-1.0) coordinate (F4)
\tkzSegment(F0/F1)
\tkzSegment(F0/F4)

% Draw grid on frustum
\tkzDrawPoint[color=black,noname](F1,F2,F3,F4)
\tkzSegment[style=dashed](F1/F4)

% Draw sphere
\path (6,0) coordinate (C)
\tkzCircleR(C,3cm)

% Draw rays
%\tkzInterLCR(F0,F2)(C,3cm){A}{B}
%\tkzSegment[style=dashed](F0/B)
\tkzInterLCR(F0,F1)(C,3cm){I1}{O1}
\tkzInterLCR(F0,F2)(C,3cm){I2}{O2}
\tkzInterLCR(F0,F3)(C,3cm){I3}{O3}
\tkzInterLCR(F0,F4)(C,3cm){I4}{O4}
\tkzSegment[style=dashed](F1/I1)
\tkzSegment[style=dashed](F0/I2)
\tkzSegment[style=dashed](F0/I3)
\tkzSegment[style=dashed](F4/I4)

	\tkzFillCircle(EP,0.1cm)

% Draw ray sphere intersections
\tkzDrawPoint[color=red,noname](I1)
\tkzDrawPoint[color=red,noname](I2)
\tkzDrawPoint[color=red,noname](I3)
\tkzDrawPoint[color=red,noname](I4)

\end{tikzpicture}

%\begin{tikzpicture}
%	\tkzInit[ymin=-1]
%	\path (0,0) coordinate(A)
%	      (6,0) coordinate(D)
%	      (8,0) coordinate(B)
%	      (4,0) coordinate(I);
%	\tkzDrawPoint[color=red](A,B,D)
%	\tkzSegment(A/B)
%	\clip (A)--(9,0)--(9,6)--(0,6)--cycle;
%	\tkzCircle*(A,B)
%	%\tkzLineOrth(A,D)(D)
%	\tkzLineOrth[kr=1,kl=0](A,D)(D)
%	\tkzInterLCR(D,dr)(I,4cm){C}{J}
%	\tkzDrawPoint[color=red,pos=above right](C)
%	\tkzLineOrth[kr=1,kl=1,prefix=t1](I,C)(C)
%	\tkzLineOrth[kr=1,kl=0,prefix=t2](A,B)(B)
%	\tkzInterLL[color=red](C,t1r)(B,t2r){T}
%	\tkzInterLL[color=red](A,T)(C,D){P}
%	\tkzSegment(A/T)
%\end{tikzpicture}

%\begin{tikzpicture}[scale = 1.75]
%   \tkzInit[xmax = 8,ymax=8] \tkzClip
%   \tkzPoint*(0,0){B} \tkzPoint*(8,0){C}%
%   \tkzPoint*(0,8){A} \tkzPoint*(8,8){D}
%   \tkzPolygon(B,C,D,A)
%   \path[clip] (B)--(C)--(D)--(A)--cycle;
%   \tkzPoint*(4,8){F}\tkzPoint*(4,0){E}\tkzPoint*(4,4){Q}
%   \tkzTgtFromP(F,F,A)(B){G}{H}
%   \tkzInterLL*(F,G)(C,D){J}
%   \tkzInterLL*(A,J)(F,E){K}
%   \tkzProjection*(B,A)(K/M)
%   \tkzFillPolygon[color = green](A,B,C,D)
%   \tkzCircle[style = {fill = orange}](B,A)
%   \tkzCircle[style = {fill = blue!50!black}](M,A)
%   \tkzCircle[style = {fill = purple}](E,B)
%   \tkzCircle[style = {fill = yellow}](K,Q)
%\end{tikzpicture}
%
%\begin{tikzpicture}
%   \tkzInit[xmin=-1,xmax=1.2,xstep=.2,ymin=-1,ymax=1.2,ystep=.2]
%   \tkzX[gradsize=\scriptstyle]
%   \tkzY[gradsize=\scriptstyle]
%   \tkzPoint(0,0){O}
%   \tkzPoint[pos=above right](1,0){A}
%   \FPcos\Mx{1}\FPsin\My{1}
%   \tkzPoint[pos=above right](1,1){T}
%   \tkzPoint[coord,%
%             mark     = *,%
%             size     = 1pt,%
%             pos      = above right](\Mx,\My){M}
%   \tkzSegment[color=red,colorlabel=red,label=1\,u](A/T,O/M)
%   \draw[color=blue] (0,0) circle (5cm);
%   \path (A) arc (0:40:5) node[rotate=-45,above,color=red] {1\,u};
%   \begin{scope}
%   \path[clip](O)--(A)--(M)--cycle;
%   \draw[color=blue,fill=red] (0,0) circle (.5cm);
%   \end{scope}
%   \begin{scope}
%   \path[clip](O)--(A)--(T)--(M)--cycle;
%   \draw[color=red] (0,0) circle (5cm);
%   \end{scope}
%   \path[clip] (0,0) circle (5cm);\tkzGrid(-1,-1)(1,1)
%   \tkzText[color= red](0.3,0.15){$1$\,rad}
%   \tkzText[style={draw},color= red](0.55,-0.15){$\scriptstyle\cos(1)$}
%  \tkzText[style={draw},color= red](-0.23,0.83){$\scriptstyle\sin(1)$}
% \end{tikzpicture}  
% 
%\begin{tikzpicture}
%    \tkzInit\tkzClip
%    \tkzPoint[pos=below right](2,1){A}%
%    \tkzPoint[pos=below](9,4){B}%
%    \tkzPoint[pos=below left](3,7){C}%
%    \tkzLine(A/B,B/C,A/C)
%    \tkzBisector[kl=0,kr=3,color=blue,style=dashed](B,A,C){x}
%    \tkzBisector[kl=0,kr=3,color=blue,style=dashed](A,B,C){y}
%    \tkzInterLL(A,x)(B,y){I}
%    \tkzProjection*(A,B)(I/c)
%    \tkzProjection*(A,C)(I/b)
%    \tkzProjection*(B,C)(I/a)
%    \tkzSegment[color=red,style=dotted,lw=1pt](I/a,I/b,I/c)
%    \tkzRightAngle(A/c/I,B/a/I,C/b/I)
%    \tkzMarkAngle[size = 1,%
%        style = ai,%
%        fillcolor = red!50](I/A/C)
%    \tkzMarkAngle[size = 0.75,%
%        style = ai,%
%        fillcolor = red!50](I/A/B)
%    \tkzMarkAngle[size = 1,%
%        style = aii,%
%        fillcolor = blue!50](I/B/C)
%    \tkzMarkAngle[size = 0.75,%
%        style = aii,%
%        fillcolor = blue!50](I/B/A)
%    \tkzCircle(I,a)
%\end{tikzpicture}
