Question

A pyramid has a base in the shape of a rhombus and a peak directly above the base's center. The pyramid's height is `6`, its base has sides of length `1`, and its base has a corner with an angle of `(3 pi)/8`. What is the pyramid's surface area?

Answer 1

T S A = 12.9655

Explanation:

AB = BC = CD = DA = a = 1
Height OE = h = 6
OF = a/2 = 1/2 = 0.5
`EF = sqrt(EO^2+ OF^2) = sqrt (h^2 + (a/2)^2) = sqrt(6^2+0.5^2) = color(red)(6.0208)`

Area of `DCE = (1/2)*a*EF = (1/2)*1*6.0208 = color(red)(3.0104)`
Lateral surface area `= 4*Delta DCE = 4*3.0104 = color(blue)(12.0416)`

`/_C = (3pi)/8`
Area of base ABCD `= a* a * sin /_C = 1^2 sin (3pi/8) = 0.9239`

T S A `= Lateral surface area + Base area`
T S A `=12.0416 + 0.9239 = color(purple)(12.9655)`