Lines that go uphill from left to right have positive slopes. The steeper the uphill grade, the
greater the slope.
Lines that go downhill from left to right have negative slopes. The steeper the downhill
grade, the less the slope.
Slopes of Parallel and Perpendicular Lines
Parallel lines have the same slope.
Perpendicular lines have negative-reciprocal slopes.
Circle
The equation of a circle centered at (h, k) and with radius r is:
(x − h)^2 + (y − k)^2 = r^2Parabola
The graph of the general quadratic equation y = ax^2 + bx + c is a parabola with an axis of
symmetry parallel to the y-axis.
Ellipse
The equation of an ellipse centered at the origin and with axial intersections at (± a, 0) and
(0, ± b) is:
Hyperbola
The equation of a hyperbola centered at the origin and with foci on the x-axis is: