Answer:
885.2m²
Step-by-step explanation:
a is the side length of the square at the base
h is the height of the pyramid
Given
a = 18m
Get the height using the pythagoras theorem
h² =18²-9²
h² = 324 - 81
h² = 243
h = √243
h = 15.5884m
Area of the triangle = 1/2 * 18 * 15.5884
Area of the triangle = 9 * 15.5884
Area of the triangle = 140.2956m²
Area of the 4 triangles = 4(140.2956)
Area of the 4 triangles = 561.1824m²
Base area = 18 * 18
Base area = 324m²
Total surface area = Base area + Area of the 4 triangles
Total surface area = 324 + 561.1824
Total surface area = 885.1824
Total surface area = 885.2m² (to the nearest tenth)
