From the figure, we can notice that : Surface area of the pyramid is equal to Sum of the area of the square and Sum of the areas of 4 triangles.
We know that : Area of a square is given by : Side x Side
Given : Side of the square = 3 cm
⇒ Area of the square = 3 x 3 = 9 cm²
We know that : Area of the triangle = 1/2 x Base x Height
From the figure, We can notice that, Base of each triangle = 3 cm and height of the each triangle = 3 cm
⇒ Area of one triangle = 1/2 × 3 × 3 = 4.5 cm²
Surface area of the pyramid = Surface of the square + Surface area of the 4 triangles
⇒ Surface area of the pyramid = 9 cm² + 4(4.5) cm²
⇒ Surface area of the pyramid = 9 cm² + 18 cm² = 27 cm²
Answer : Surface area of the pyramid = 27 cm²