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 3 3, its base has sides of length 5 5, and its base has a corner with an angle of pi/4 π4. What is the pyramid's surface area?

1 Answer
Feb 4, 2018

color(green)(T S A)TSA color(green)(A_T = A_L + A_R = 74.4063)AT=AL+AR=74.4063

Explanation:

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Total Surface Area of the pyramid is sum of the areas of the rhombus base (A_R)(AR) and the four side triangles (A_L= 4 * A_t)(AL=4At)
A_T = A_L + A_R = 4A_t + A_RAT=AL+AR=4At+AR

A_R = a*asin theta = 5 * 5 sin (pi/4) = 25sqrt2 = 35.3553AR=aasinθ=55sin(π4)=252=35.3553#

A_L = 4 A_t = 4 * (1/2) (a * l)# where l is the slant height of the triangle.

But l = sqrt((a/2)^2 + h^2) = sqrt((5/2)^2 + 3^2) = 3.9051l=(a2)2+h2=(52)2+32=3.9051

:. A_L = 4 * (1/2) * 5 * 3.9051 = 39.051

color(green)(T S A) color(green)(A_T = A_L + A_R = 39.051 + 35.3553 = 74.4063)