In △XYZ , XZ=9 , YZ=4 , and XY=7 .

What is the area of the triangle?

Enter your answer, in simplified radical form, in the box.

Step-by-step explanation:

we know that

Heron's Formula is a method for calculating the area of a triangle when you know the lengths of all three sides.  

so

where

a, b and c are the length sides of triangle

s is the semi-perimeter of triangle

we have

Find the semi-perimeter s  

Find the area of triangle

Simplify

i used to know how to do this in 7th but i forget easily

step-by-step explanation:

it is a. 4.2 because 7.6-3.4 gets the remaining length of 4.2. i might be wrong but i am pretty sure this is the answer.