Mathematics Question and Solution
Let the two equal red lengths of the triangle, ABC be 1 unit.
Therefore;
AB = CE = 1 unit.
a = 180-100-20
a = 60°
(b/sin100) = (1/sin20)
b = 2.8793852416 units.
b is BC.
c = 2.8793852416-1
c = 1.8793852416 units.
c is BE.
Notice;
BE = CD = the blue equal lengths.
It implies;
d² = 1+1.8793852416²-2*1*1.8793852416cos20
d = 1 unit.
d is DE.
Notice;
CE = DE = 1 unit.
Therefore;
e = 180-2(20)
e = 180-40
e = 140°
e is angle CED.
It implies;
The required angle, x is;
x+140 = 180
x = 180-140
x = 40°
x is angle BED.
