Mathematics Question and Solution
a = 108-90
a = 18°
cos18 = b/1
b = 0.9510565163 units.
c = 1+0.9510565163
c = 1.9510565163 units.
c is the side length of the regular ascribed pentagon.
sin18 = d/1
d = 0.3090169944 units.
e² = 2*1.9510565163²-2*1.9510565163²cos108
e = 3.1568757573 units.
Therefore, green area is;
Area regular pentagon with side length 1.9510565163 cm - 5(area square with side length 1 unit) - 5(area triangle with height 0.9510565163 units and base 0.3090169944 units.
= 2(0.5*1.9510565163*1.9510565163sin108)+(0.5*1.9510565163*3.1568757573sin72)-5(1*1)-5(0.5*0.9510565163*0.3090169944)
= 0.8144747491 square units.
≈ 0.81 square units to 2 decimal places.
