Ellipses - Example 1: Sketching 4x^2 + 9y^2 = 36
4x^2 + 9y^2 = 36 is the equation of an ellipse centred at the origin (0,0). Before we can sketch the ellipse, we need to find the vertices (i.e. the x and y intercepts) by transforming the equation to the standard form, which is:
x^2/a^2 + y^2/b^2
where...
a is the semi-major axis
b is the semi-minor axis
So, dividing the equation by 36, we get:
x^2/9 + y^2/4 = 1
Or...
x^2/3^2 + y/2^2 = 1
Thus a = 3 and b = 2, and hence the vertices are:
A = (3,0)
A' = (-3,0)
B = (0,2)
B' = (0,-2)
To fully define the ellipse, we should also find the focal points and the directrices. Thus we to find the eccentricity. We can do this through the relationship:
b^2 = a^2 - (ae)^2
The focal points (foci) are given by:
F = (ae,0)
F' = (-ae,0)
And the equations are of the directrices are:
x = a/e
x = -a/e
Suggested video:
- "Conic Sections: The Ellipse - Part 1" https://youtu.be/j3abHkwAFvY
Thanks for watching. Please give me a "thumbs up" if you have found this video helpful.
Please ask me a maths question by commenting below and I will try to help you in future videos.
Follow me on Twitter! twitter.com/MasterWuMath
Видео Ellipses - Example 1: Sketching 4x^2 + 9y^2 = 36 канала MasterWuMathematics
x^2/a^2 + y^2/b^2
where...
a is the semi-major axis
b is the semi-minor axis
So, dividing the equation by 36, we get:
x^2/9 + y^2/4 = 1
Or...
x^2/3^2 + y/2^2 = 1
Thus a = 3 and b = 2, and hence the vertices are:
A = (3,0)
A' = (-3,0)
B = (0,2)
B' = (0,-2)
To fully define the ellipse, we should also find the focal points and the directrices. Thus we to find the eccentricity. We can do this through the relationship:
b^2 = a^2 - (ae)^2
The focal points (foci) are given by:
F = (ae,0)
F' = (-ae,0)
And the equations are of the directrices are:
x = a/e
x = -a/e
Suggested video:
- "Conic Sections: The Ellipse - Part 1" https://youtu.be/j3abHkwAFvY
Thanks for watching. Please give me a "thumbs up" if you have found this video helpful.
Please ask me a maths question by commenting below and I will try to help you in future videos.
Follow me on Twitter! twitter.com/MasterWuMath
Видео Ellipses - Example 1: Sketching 4x^2 + 9y^2 = 36 канала MasterWuMathematics
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