# Thread: when we use standerd Equation of an ellipse

1. ## when we use standerd Equation of an ellipse

Hi

when we use standerd Equation of an ellipse

here 2 formula 1 and 2 when we use 1 and when we use 2

hlep me

2. when we say a is called b and b is called a in the queation
i mean in queation how we nowthe solve will be by formula 1 or 2
help me >>

3. Originally Posted by r-soy
when we say a is called b and b is called a in the queation
i mean in queation how we nowthe solve will be by formula 1 or 2
help me >>
a is always the larger of the two, in the equations given. If a^2 is underneath x^2 then the ellipse will be oriented horizontally. Otherwise the ellipse will be oriented vertically.

If a and b are equal then you have a circle.

4. There are textbooks in which the "standard equation" for an ellipse is given as $\displaystyle \frac{x^2}{a^2}+ \frac{y^2}{b^2}= 1$ with "a" and "b" always being the lengths to semi-axes in the x and y directions respectively, irrespective of which is longer.

Lesson: don't just memorize formulas, learn what they mean!