Question

Find the surface area of regular prism with height 6 cm, if the base of the prism is: a Equilateral triangle with the side 3 cm and altitude of the triangle of approximately 2.6 cm.

Answer 1

we know that
[surface area]=2*[area of the base]+[perimeter of the base]*height of prism

area of the base= area of a equilateral triangle
b=3 cm
h=2.6 cm
area of the base=b*h/2-----> 3*2.6/2----> 3.9 cm²

perimeter of the base=perimeter of a equilateral triangle
b=3 cm
perimeter=3*(3)-----> 9 cm

[surface area]=2*[area of the base]+[perimeter of the base]*height of prism
[surface area]=2*[3.9]+[9]*6-----> 7.8+54-----> 61.8 cm²

the answer is
61.8 cm²