Ok so,
#1 is a triangular pyramid as we can see.
The surface area formula of a pyramid is:
S.A = Area of base + \(\frac{1}{2}\) × perimeter of base × slant height
The base is 8 cm ( 4cm + 4cm = 8cm)
Height of the triangle is 3.5 cm
Area formula of a triangle is:
A = \(\frac{1}{2}\)bh
P = all sides added together
Substitute them:
S.A = \(\frac{1}{2}\) × 8 × 3.5 + \(\frac{1}{2}\) ×(8 + 8 + 8) × 5
S.A = 14 + 60
= 74 cm²
and #2 is a squared-based pyramid
Same formula applies.
And we know that the area formula of a square is:
A = s²
P = add all sides together
S.A = 2² + \(\frac{1}{2}\) × (2 + 2 + 2 + 2) × 3
= 4 + 12
= 16 ft²
