Item:Q7812: Difference between revisions

@@ Property / has quality @@
+area of plane shape
@@ Property / has quality: area of plane shape / rank @@
+Normal rank
@@ Property / has quality: area of plane shape / qualifier @@
+defining formula:  $A={\frac {5}{4}}t^{2}\mathop {\mathrm {ctg} } \,{\frac {\pi }{5}}={\frac {{\sqrt {5}}{\sqrt {5+2{\sqrt {5}}}}}{4}}t^{2}={\frac {5}{12}}Rd$ 
A=\frac{5}{4} t^2 \mathop{\mathrm{ctg}}\, \frac{\pi}{5} = \frac{\sqrt 5 \sqrt{5 + 2 \sqrt{5}}}{4} t^2 = \frac{5}{12}Rd