# Rockefeller Center Christmas Tree – The SolutionsDecember 8, 2008

(½)(72)(40) = 1440 sq feet

√(722 + 202) = √5584 = 74.73 feet
SA = πrs + πr2, when s = lateral height (or slant height). However, if lights aren’t strung on the base, we can subtract πr2 from the equation. This leaves us with A = πrs. Based on the previous problem we know that s = 74.73 feet, thus SA = π (20)(74.73) = 4695.42 sq feet.

Now we divide the number of LEDs by the square footage.

30,000/4695.42 = 6.4 LEDs per square foot, to the nearest tenth.

[(3510 – 1297)/3510] × 100 = 63%

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