Question

I need to know the surface area. The formula is Area Of Base + Area of lateral faces

Answer 1

Answer:

215.1 yd²

Step-by-step explanation:

We have three triangles with base b = 9yd and height h = 10yd, and one triangle in the base of pyramid with base b = 9yd and height h = 7.8yd.

The formula of an area of a triangle:

$A_\triangle=\dfrac{bh}{2}$

Substitute:

$LA=4\cdot\dfrac{(9)(10)}{2}=(2)(90)=180\ yd^2\\\\B=\dfrac{(9)(7.8)}{2}=(9)(3.9)=35.1\ yd^2\\\\SA=B+LA\to SA=180+35.1=215.1\ yd^2$