# How can I calculate the focus of a parabola?

Apr 15, 2017

$\text{please have a look the fallowing details.}$

#### Explanation:

$\text{if you have an equation in the vertex form "f=a(x-h)^2+k ,}$
$\text{focus is } \left(h , k + \frac{1}{4 a}\right)$

$\text{example :}$

$y = 2 \left(x - 1\right) + 1$

$a = 2 \text{ , "h=1" , } k = 1$

$\text{Focus } A = \left(h , k + \frac{1}{4 a}\right)$

$A = \left(1 , 1 + \frac{1}{4 \cdot 2}\right)$

$A = \left(1 , 1 + \frac{1}{8}\right)$

$A = \left(1 , \frac{9}{8}\right)$