The surface area of the pyramid is 576.
<em>The square base is 144. It's just a square, so you multiply 12 (length) and 12 ( width) , which equals 144. </em>
<em>Then you find the area of one of the triangles. The equation to find triangles goes like this: 0.5 x B (base: 12) x H (height: 18). That would be 6 x 18 which is 108.</em>
<em>Since you got the area of 1 triangle and there are 4 triangles you have to multiply 108 by 4. That'll give you 432.</em>
<em>SO since you have the area of all the triangles and the square base the last thing you have to do is just add it all up. </em>
<em>The area of the triangles plus the area of the square base = the surface area.</em>
<u>432 cm + 144 cm =576 cm.</u>