A pyramid has a parallelogram shaped base and a peak directly above its center. Its base's sides have lengths of 8 8 and 2 2 and the pyramid's height is 9 9. If one of the base's corners has an angle of (5pi)/125π12, what is the pyramid's surface area?

1 Answer
May 3, 2018

color(maroon)("Total Surface Area " = color(purple)(A_T = A_B + A_L = color(crimson)(15.45 + 94.12 = 109.57Total Surface Area =AT=AB+AL=15.45+94.12=109.57

Explanation:

https://socratic.org/questions/a-pyramid-has-a-parallelogram-shaped-base-and-a-peak-directly-above-its-center-i-95https://socratic.org/questions/a-pyramid-has-a-parallelogram-shaped-base-and-a-peak-directly-above-its-center-i-95

l = 8, b = 2, theta = (5pi)/12, h = 9l=8,b=2,θ=5π12,h=9

"To find the Total Surface Area T S A"To find the Total Surface Area T S A

"Area of parallelogram base " A_B = l b sin thetaArea of parallelogram base AB=lbsinθ

A_B = 8 * 2 * sin ((5pi)/12) = 15.45AB=82sin(5π12)=15.45

S_1 = sqrt(h^2 + (b/2)^2) = sqrt(9^2 + 1^2) = 9.06S1=h2+(b2)2=92+12=9.06

S_2 = sqrt(h^2 + (l/2)^2) = sqrt(9^2 + 4^2) = 10.82S2=h2+(l2)2=92+42=10.82

"Lateral Surface Area " A_L = 2 * ((1/2) l * S_1 + (1/2) b * S_2Lateral Surface Area AL=2((12)lS1+(12)bS2

A_L = (cancel2 * cancel(1/2)) * (l * S_1 + b * S_2) = (8 * 9.06 + 2 * 10.82)

A_L = 94.12

"Total Surface Area " A_T = A_B + A_L = 15.45 + 94.12 = 109.57