Education Technology

Algebra II: Properties of Parabolas
by Texas Instruments

Published on February 15, 2011


Students interpret the equation for a parabola in vertex form and gain a visual understanding of a parabola's focal width.

Key Steps

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    In the first problem, students are introduced to the terms focus and directrix. Through a graphing investigation, students will see that the distance from a point of the parabola to the focus is the same as the distance from the same point to the directrix.

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    In the second problem, students will use the Cabri™ Jr. app to reaffirm their conclusion from the first problem and then see how the shape of the parabola changes as the focus is moved closer and farther away from the vertex. Students will also determine an equation for the parabola through use of the measurement tool.