M2=5x+10
.................
Surface area of a square pyramid is the area of the base + 4 times the area of one of the slanted sides.
Area of base = side length * side length
Area of side = (1/2) * side length * slant height
Don't forget that you have to multiply the area of the side by 4!
Step 1: 12 x 12 = 144
Step 2: 12 x 20 = 240 divided by 2 = 120
Step 3: 144 + 120 x 4
By the Pythagorean theorem
.. x = √((2√3)^2 -(√6)^2) = √(12 -6) = √6 . . . . cm
x = √6 cm
