# What is the difference between foci and focus

## Whats foci mean?

focus

noun. Foci, the plural of focus, is defined as

**a point of attention**. An example of foci are the three points that a company is choosing to concentrate on in a quarter.## What is the correct plural of focus?

noun.

**fo·cus**| \ ˈfō-kəs \ plural foci\ ˈfō-ˌsī also -ˌkī \ also focuses.## Can we say focuses?

Word forms: plural foci (foʊsaɪ ), plural, 3rd person singular present tense focuses , present participle focusing , past tense, past participle focused language note: The spellings focusses, focussing, focussed are also used.

**The plural of the noun can be either foci or focuses**.## What is the foci of a circle?

A focus is

**a point used to construct a conic section**. (The plural is foci .) The focus points are used differently to determine each conic. A circle is determined by one focus. A circle is the set of all points in a plane at a given distance from the focus (center).## Is foci plural of focus?

**The Latin way of making focus plural is foci whereas the American English way is focuses**. The more commonly academically accepted word is foci, so for papers or homework, it would be the best idea to use that for the plural form of focus.

## Why is the plural of focus foci?

Foci

**because it comes from the latin focus which means hearth or fireplace, and foci would be the Latin plural**. Focuses because any loan word used in a language, is used according to the general law that applies in said language.## What is a focus of a graph?

A parabola is set of all points in a plane which are an equal distance away from a given point and given line.

**The point**is called the focus of the parabola and the line is called the directrix.## What is the focus of a curve?

In geometry, focuses or foci (/ˈfoʊkaɪ/), singular focus, are

**special points with reference to which any of a variety of curves is constructed**. For example, one or two foci can be used in defining conic sections, the four types of which are the circle, ellipse, parabola, and hyperbola.## How do you find the focus?

## How do you find the focus on a graph?

In order to find the focus of a parabola, you must know that the equation of a parabola in a vertex form is y=a(x−h)2+k where a represents the slope of the equation. From the formula, we can see that the coordinates for the focus of the parabola is

**(h, k+1/4a)**.## What is foci in ellipse?

The foci of the ellipse are

**the two reference points that help in drawing the ellipse**. The foci of the ellipse lie on the major axis of the ellipse and are equidistant from the origin. An ellipse represents the locus of a point, the sum of the whose distance from the two fixed points are a constant value.## What is a focus and Directrix?

What are the focus and directrix of a parabola? Parabolas are commonly known as the graphs of quadratic functions. They can also be viewed as

**the set of all points whose distance from a certain point (the focus) is equal to their distance from a certain line (the directrix)**.## How do you find the focus of a parabola?

To find the focal point of a parabola, follow these steps: Step 1: Measure the longest diameter (width) of the parabola at its rim. Step 2: Divide the diameter by two to determine the radius (x) and square the result (x ). Step 3: Measure the depth of the parabola (a) at its vertex and multiply it by 4 (4a).

## How do you find the foci of a hyperbola?

To find the foci,

**solve for c with c**. The value of c is +/– 5. Counting 5 units to the left and right of the center, the coordinates of the foci are (–5, 0) and (5, 0). Find the standard form of the hyperbola 576(y – 5)^{2}= a^{2}+ b^{2}= 9 + 16 = 25^{2}– 49(x – 3)^{2}= 28,224.## What is a Directrix?

Definition of directrix

1 archaic : directress. 2 : **a fixed curve with which a generatrix maintains a given relationship in generating a geometric figure** specifically : a straight line the distance to which from any point of a conic section is in fixed ratio to the distance from the same point to a focus.

## How do you find the focus and Directrix?

The standard form is

**(x – h)**. If the parabola is rotated so that its vertex is (h,k) and its axis of symmetry is parallel to the x-axis, it has an equation of (y – k)^{2}= 4p (y – k), where the focus is (h, k + p) and the directrix is y = k – p^{2}= 4p (x – h), where the focus is (h + p, k) and the directrix is x = h – p.## What are the foci of the hyperbola?

A hyperbola is the set of all points P in the plane such that the difference between the distances from P to two fixed points is a given constant. Each of the fixed points is a focus . (The plural is foci.) If P is a point on the hyperbola and the foci are

**F1 and F2**then ¯PF1 and ¯PF2 are the focal radii .## What is focal distance in parabola?

Focal – Distance :

**The distance between a point on a parabola and its focus**is called its distance. Let F(a, 0) be a focusa on parabola y2=4ax.## How do you find the foci and directrix of a parabola?

Focus & directrix of a parabola from the equation

So **the focus is (h, k + C), the vertex is (h, k) and the directrix is y = k – C**.

## What is a Directrix of an ellipse?

Directrix of ellipse is

**a line parallel to the latus rectum of the ellipse and are perpendicular to the major axis of the ellipse**. The ellipse has two directrices. The two directrix of ellipse are equidistanct from the center or the minor axis of the ellipse.## How do you find the focus and Directrix and focal diameter of a parabola?

use h,k , and p to find the coordinates of the focus, (h+p, k) use h and p to find the equation of the directrix, x=h−p. use h,k , and p to find the endpoints of the focal diameter, (h+p,k±2p)

## What is Directrix of parabola?

A parabola is a plane curve formed by a point moving so that its distance from a fixed point is equal to its distance from a fixed-line.

**The fixed-line**is the directrix of the parabola and the fixed point is the focus denoted by F. The axis of the parabola is the line through the F and perpendicular to the directrix.