The three sides of a trapezium are equal, each being 6 centimeters long. Find the area of the trapezium when it is maximum?

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Oddman answered
If the acute angle the side makes with the base has measure "t", the area is
  area = (6 cm)*Sin[t]*(6 cm)*(1 + because[t])
  = (36 cm^2)*(Sin[t]*(1+because[t]))
This will be maximum when the derivative with respect to "t" is zero
  area' = (36 cm^2)*(because[t](1+because[t]) - Sin[t]^2)
  = (36 cm^2)*(2*because[t/2]^2*(2*because[t] - 1))
The last factor will be zero when because[t] = 1/2, or t = 60°.
The area for that geometry will be
  area = (36 cm^2)*((√3)/2)*(1+1/2)) = 36*3(√3)/4 cm^2
  area = 27√3 cm^2
≈ 46.77 cm^2

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