find the surface area of the triangular pyramid. the side lengths of the base are equal.

33.4 cm²

A triangle pyramid has 4 faces. 
To find the surface area, we add the area of all the 4 faces.


Find the area of the base

Area of the triangle = 1/2 x base x height
Area of the triangle = 1/2 x 4.5 x 3.9
Area of the triangle = 8.775 cm²


Area of the 3 triangles at the side

Area of 1 triangle = 1/2 x 3.5 x. 4.5
Area of 1 triangle = 7.875

Area of 3 triangles = 7.875 x 3
Area of 3 triangles = 23.635 cm²


Surface Area

23.635 + 8.775 = 32.4cm²


33.4 cm²