What is the surface area of this square pyramid?Round your answer to the nearest tenth.
Question
Answer:
The question is to find the surface area of the square pyramid:This pyramid encloses a volume V, so it has five surfaces, namely:
*One square base.
*four triangular surfaces.
1. Surface area of the square base:
All four sides are equal, so:
As = LxL = (8.4yd)(8.4yd) = 70.56[tex]yd^2[/tex]
2. Area of triangular surfaces:
Given that the angle β=60°, we have four equilateral triangles which have three equal sides each, therefore:
At = [tex] 4(\frac{base.height}{2}) [/tex] = [tex]2L.Ap[/tex]
Now we need to calculate the apothem Ap.
Using trigonometry, we can calculate Ap using the sine function:
sinβ = [tex] \frac{opposite}{hypotenuse} [/tex] = [tex] \frac{Ap}{a} [/tex]
Given that the triangles are equilateral, then a = L
∴ Ap = (a)(sinβ) = 8.4sin(60°) = (8.4)([tex] \frac{ \sqrt{3} }{2} [/tex]) = 7.275yd
So:
[tex]At = 2(8.4)(7.275) = 122.22 yd^{2}[/tex]
Therefore, the surface area of the pyramid is:
A = As + At = 70.56 + 122.22 = 192.78 [tex] yd^{2} [/tex]
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