What is the area of a decagon with a side length of 4cm?

3 answers

You would have 10 congruendt isosceles triangles,
each with a top angle of 36° , and equal base angles of
72°
We need the height:
height/2 = tan 72°
height = 2tan72°
area of each triangle = (1/2)base x height
= (1/2)(4)(2tan72°) = 4tan72°

so area of decagon = 10(4tan72°) = ....

you do the button-pushing.
4cm
so sussy balls