#### Answer

The length of equal legs of the isosceles triangle is 14.14 centimeter.

#### Work Step by Step

We will use Pythagoras theorem to find out the length of each leg.
By Pythagoras theorem,
$P^2+B^2=H^2$
Where,
P= Perpendicular
B= Base
H= Hypotenuse
Here $P=B=x$ and $H=20$
Step-1: Substituting in the formula,
$x^2+x^2=20^2$
$2x^2=400$
Step 2: Dividing both sides by 20
$x^2=\frac{400}{2}$
$x^2=200$
Step-3: Using the square root property
$x=±\sqrt200$
$x=±14.1421$
Since the leg of isosceles triangle cannot be negative, the length is approximately 14.14 centimeters.