Pentagon

Calculate the area of a regular pentagon, which diagonal is u=16.

Correct answer:

S =  168.23

Step-by-step explanation:

u=16 n=5  A=(180360/n)/2=(180360/5)/2=54  B=2360/n=2360/5=36   sinA=u/2:a a=u/2/sin(A)=16/2/sin(54°)9.8885  tanB=a/2:h h=a/2/tan(B)=9.8885/2/tan(36°)6.8052  S1=2a h=29.8885 6.805233.6468 S=n S1=5 33.6468=168.23



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