The lateral area would be 298.7 cm².
The lateral area is the area of all of the lateral faces of the pyramid. There are 8 triangles making up the lateral faces. Each has a base of 6.6. The formula for the area of a triangle is
A=1/2bh,
so we still need the height of the triangle.
The height of each lateral triangle is the slant height of the pyramid. The slant height of the pyramid forms a right triangle with the height of the pyramid and the "radius" as it were of the pyramid. Thus we use the Pythagorean theorem:
8²+8²=h²
64+64=h²
128=h²
√128=√(h²)
8√2 = h
Substituting this into our area formula we have:
A=1/2(6.6)(8√2)
We will go ahead and multiply this by 8, since there are 8 lateral faces:
LA=8(1/2)(6.6)(8√2)
LA = 298.7
If you mean the sum of the two square roots, it would be 11. The square root of 25 = 5 and the square root of 36 = 6.. and 5 + 6 = 11
