I need help with this geometry question
1 answer:
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Answer:
Step-by-step explanation:
1. Area of base
The radius given is that of the circumcircle.
The general formula for the edge length a of a regular polygon is
a = 2Rsin(π/n)
So,
a = 2 × 5 × sin(π/5) = 10sin0.6283 = 10 × 0.5878 = 5.878 in
The general formula for the area of a regular polygon is
A = ¼na²cot(π/n)
So,
A = ¼ × 5 × 5.878²cot(π/5) = ¼ × 5 × 5.878² × 1.376 = 59.44 in²
2. Lateral area
The general formula for the lateral area L of regular prism is
L = nah
So,
L = 5 × 5.878 × 12 = 352.7 in²
3. Total area
Total surface area = lateral area + 2×base area
S = L + 2B = 352.7 + 2 × 59.44 = 471.6 in²