ClipArt ETC
Illustration of a regular pentagon circumscribed about a circle. This can also be described as a circle inscribed in a regular pentagon.

Regular Pentagon Circumscribed About A Circle

Illustration of a regular pentagon circumscribed about a circle. This can also be described as a circle…

Illustration of a regular pentagon inscribed in a circle. This can also be described as a circle circumscribed about a regular pentagon.

Regular Pentagon Inscribed In A Circle

Illustration of a regular pentagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustration showing how the golden ratio in a regular pentagon (inscribed in a circle) can be found using Ptolemy's theorem. The lines that are bolded form a quadrilateral. Ptolemy's theorem says the square of b equals the sum of a squared and ab, which in turn gives the golden ratio.

Golden Ratio In A Pentagon

Illustration showing how the golden ratio in a regular pentagon (inscribed in a circle) can be found…