Pentagon

Calculate the length of side, circumference and area of a regular pentagon, which is inscribed in a circle with radius r = 6 cm.

Correct result:

a =  7.0534 cm
o =  35.2671 cm
S =  85.5951 cm2

Solution:

r=6 a=2 r sin(π/5)=2 6 sin(3.1416/5)=7.0534 cm
o=5 a=5 7.0534=35.2671 cm
h=r2(a/2)2=62(7.0534/2)24.8541 S1=a h/2=7.0534 4.8541/217.119 S=5 S1=5 17.119=85.5951 cm2



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Pythagorean theorem is the base for the right triangle calculator.
See also our trigonometric triangle calculator.

 
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