30-gon

At a regular 30-gon, the radius of the inscribed circle is 15cm. Find the side length a, circle radius R, circumference, and area.

Correct answer:

a =  3.1531 cm
R =  15.0826 cm
o =  94.5938 cm
S =  709.4536 cm2

Step-by-step explanation:

r=15 n=30 A=360/n=360/30=12  cos A/2 = r/R R=r/cos(A/2)=15/cos(12/2)15.0826 (a/2)2 = R2  r2 x=R2r2=15.082621521.5766 a=2 x=2 1.5766=3.1531 cm
o=n a=30 3.1531=94.5938 cm
S1=a r/2=3.1531 15/223.6485 S=n S1=30 23.6485=709.4536 cm2



Did you find an error or inaccuracy? Feel free to write us. Thank you!







Tips for related online calculators
See also our right triangle calculator.
See also our trigonometric triangle calculator.

You need to know the following knowledge to solve this word math problem:


 
We encourage you to watch this tutorial video on this math problem: video1   video2

Related math problems and questions: