Answer :

To calculate the surface area of a square pyramid using the formula [tex]\( A = \text{Base Area} + \text{Lateral Surface Area} \)[/tex], we'll break it down into a step-by-step solution.

### Step 1: Determine the Base Area

The base of a square pyramid is a square. The area of a square base is calculated using the formula:
[tex]\[ \text{Base Area} = s^2 \][/tex]
where [tex]\( s \)[/tex] is the length of a side of the square base. For this problem, the side length [tex]\( s \)[/tex] is 5 units.

[tex]\[ \text{Base Area} = 5^2 = 25 \, \text{square units} \][/tex]

### Step 2: Determine the Lateral Surface Area

The lateral surface area of a square pyramid consists of the areas of the four triangular faces. Each face is an isosceles triangle with a base [tex]\( s \)[/tex] and height [tex]\( l \)[/tex] (the slant height of the pyramid). The area of one such triangle is given by:

[tex]\[ \text{Area of one triangle} = \frac{1}{2} \times \text{base} \times \text{height} \][/tex]

Since there are four triangles,

[tex]\[ \text{Lateral Surface Area} = 4 \times \frac{1}{2} \times s \times l \][/tex]

Simplifying,

[tex]\[ \text{Lateral Surface Area} = 2 \times s \times l \][/tex]

Given [tex]\( s = 5 \)[/tex] units and [tex]\( l = 10 \)[/tex] units:

[tex]\[ \text{Lateral Surface Area} = 2 \times 5 \times 10 = 100 \, \text{square units} \][/tex]

### Step 3: Calculate the Total Surface Area

Finally, add the base area and the lateral surface area to get the total surface area of the square pyramid:

[tex]\[ A = \text{Base Area} + \text{Lateral Surface Area} \][/tex]

[tex]\[ A = 25 \, \text{square units} + 100 \, \text{square units} \][/tex]

[tex]\[ A = 125 \, \text{square units} \][/tex]

### Summary

- Base Area: [tex]\( 25 \, \text{square units} \)[/tex]
- Lateral Surface Area: [tex]\( 100 \, \text{square units} \)[/tex]
- Total Surface Area: [tex]\( 125 \, \text{square units} \)[/tex]

Thus, the total surface area of the square pyramid is [tex]\( 125 \, \text{square units} \)[/tex].