The quadratic function $f(x)=a(x-h)^2+k$ is in standard form.
(a) The graph of $f$ is a parabola with vertex (_____,_____)
(b) If $a>0$, the graph of $f$ opens _____ . In this case $f(h)=k$ is the value _____ of $f$.
(c) If $a<0$, the graph of $f$ opens _____ . In this case $f(h)=k$ is the value _____ of $f$.