Graphing Parabolas Without T-charts!

What’s the equation for a parabola? Either y = ax2 + bx + c Or y = a(x – h)2 + k We’re using this one from here on out

What’s a parabola look like? A U Or, like this:

There are many parts to a parabola

Stuff we already know Axis of Symmetry: x = h or y = k Vertex = (h, k) Also, which direction does it open? Up/Right if a is positive, Down/Left if a is negative

Focus Always at the same relative point: For vertical parabola: (h, k + (1/4a)) For horizontal parabola: (h + (1/4a), k)

Directrix A line, either horizontal or vertical, that sits below the parabola. Equation: y = k – (1/4a) Or x = h – (1/4a)

Latus Rectum It always passes through the focus, parallel to the directrix (which means it’s horizontal/vertical) It’s always the same length: |1/a|