Find the Foci ((x+15)^2)/676+((y-4)^2)/100=1

$\frac{{(x + 15)}^{2}}{676} + \frac{{(y - 4)}^{2}}{100} = 1$

Step 1

Simplify each term in the equation in order to set the right side equal to $1$ . The standard form of an ellipse or hyperbola requires the right side of the equation be $1$ .

$\frac{{(x + 15)}^{2}}{676} + \frac{{(y - 4)}^{2}}{100} = 1$

Step 2

This is the form of an ellipse. Use this form to determine the values used to find the center along with the major and minor axis of the ellipse.

$\frac{{(x - h)}^{2}}{a^{2}} + \frac{{(y - k)}^{2}}{b^{2}} = 1$

Step 3

Match the values in this ellipse to those of the standard form. The variable $a$ represents the radius of the major axis of the ellipse, $b$ represents the radius of the minor axis of the ellipse, $h$ represents the x-offset from the origin, and $k$ represents the y-offset from the origin.

$a = 26$

$b = 10$

$k = 4$

$h = - 15$

Step 4

Find $c$ , the distance from the center to a focus.

Find the distance from the center to a focus of the ellipse by using the following formula.

$\sqrt{a^{2} - b^{2}}$

Substitute the values of $a$ and $b$ in the formula.

$\sqrt{{(26)}^{2} - {(10)}^{2}}$

Simplify.

Raise $26$ to the power of $2$ .

$\sqrt{676 - {(10)}^{2}}$

Raise $10$ to the power of $2$ .

$\sqrt{676 - 1 \cdot 100}$

Multiply $- 1$ by $100$ .

$\sqrt{676 - 100}$

Subtract $100$ from $676$ .

$\sqrt{576}$

Rewrite $576$ as $24^{2}$ .

$\sqrt{24^{2}}$

Pull terms out from under the radical, assuming positive real numbers.

$24$

Step 5

Find the foci.

The first focus of an ellipse can be found by adding $c$ to $h$ .

$(h + c, k)$

Substitute the known values of $h$ , $c$ , and $k$ into the formula.

$(- 15 + 24, 4)$

Simplify.

$(9, 4)$

The second focus of an ellipse can be found by subtracting $c$ from $h$ .

$(h - c, k)$

Substitute the known values of $h$ , $c$ , and $k$ into the formula.

$(- 15 - (24), 4)$

Simplify.

$(- 39, 4)$

Ellipses have two foci.

${Focus}_{1}$ : $(9, 4)$

${Focus}_{2}$ : $(- 39, 4)$

${Focus}_{1}$ : $(9, 4)$

${Focus}_{2}$ : $(- 39, 4)$

Step 6

Find the Foci ((x+15)^2)/676+((y-4)^2)/100=1

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