Question

2. A pyramidal monument has an octagonal base, each side of which is 2 m. Each lateral edge of the pyramid is 3m. Find the total cost of painting the lateral surface of the monument at PhP 730.00 per square meter?

Answer 1

Given, octagonal Base $\implies$ 8 Triangles.

base of each triangle is 2m.

other sides measure 3m.

area of one triangle =$\sqrt{(s*(s-a)*(s-b)*(s-c))}$

total lateral surface area = 8 * area of one triangle

= 8 * 2.83 m²

= 22.63 m² (approximately)

Total cost = rate * area

= PhP 730 * 22.63

= PhP 16,520