FP3.2.2 - Focus-directrix properties

The focus-directrix properties of For example, students should know that, for the ellipse, the ellipse and hyperbola, including b2 = a2(1 − e2), the foci are (ae, 0) and (−ae, 0) and the the eccentricity. equations of the directrices are a a x = + and x = −. e e.

Use fp3.2.2 - focus-directrix properties to connect the rule to the data and decision in the question.

This matters because fp3.2.2 - focus-directrix properties determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply fp3.2.2 - focus-directrix properties to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: FP3.2.2 - Focus-directrix properties is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.