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penfila11Pen
Ok so,
#1 is a triangular pyramid as we can see.
The surface area formula of a pyramid is:
S.A = Area of base + [tex] \frac{1}{2} [/tex] × 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 = [tex] \frac{1}{2} [/tex]bh
P = all sides added together

Substitute them:
S.A = [tex] \frac{1}{2} [/tex] × 8 × 3.5 + [tex] \frac{1}{2} [/tex] ×(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 + [tex] \frac{1}{2} [/tex] × (2 + 2 + 2 + 2) × 3
       = 4 + 12
       = 16 ft²

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