# ALEX Classroom Resource

## Finding the Foci of an Ellipse From an Equation

Classroom Resource Information

Title:

Finding the Foci of an Ellipse From an Equation

URL:

Content Source:

Other
Type: Learning Activity

Overview:

In this instructional video and practice activity from Khan Academy, students will explore how the radii and the foci of an ellipse relate to each other and how this relationship can be used to find the foci from the equation of an ellipse. This video can be used during a lesson on solving systems of equations. The video is 13 minutes and 48 seconds in length and can be assigned through Google Classroom. There are practice problems included after the video.

Content Standard(s):
 Mathematics MA2015 (2016) Grade: 9-12 Precalculus 37 ) (+) Derive the equations of ellipses and hyperbolas given the foci, using the fact that the sum or difference of distances from the foci is constant. [G-GPE3]
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Partnered Event: ALEX Resource Development Summit
AccessibilityVideo resources: includes closed captioning or subtitles

2019 ALCOS

Precalculus

37. Use trigonometric identities to solve problems.

a. Use the Pythagorean identity sin^2 (θ) + cos^2(θ) = 1 to derive the other forms of the identity.
Example: 1 + cot^2 (θ) = csc^2 (θ)

b. Use the angle sum formulas for sine, cosine, and tangent to derive the double angle formulas.

c. Use the Pythagorean and double angle identities to prove other simple identities.

This resource provided by:
 Author: YVETTE AKRIDGE The event this resource created for: ALEX Resource Development Summit