I'm assuming that the problem is with the peak.
There are four congruent triangles, each with a base of 8.
We need to find the slant height of this pyramid; this will be the height of each triangle.
To find this length, consider a right triangle from the top point to the middle of the base and over to the middle of each side.
The length from the top point straight down to the middle of the base is 8.
The length from the middle of the base to the middle of one side is 4.
Therefore the slant height is the hypotenuse of this triangle: c2 = 42 + 82 ---> c = sqrt(80)
So, each triangle has an area of ½·8·sqrt(80) and there are four of these triangles.
The base is 8 x 8.
Each side is 8 x 13.
Now, its calculator time ...