Question 1013496
cot^2(a)= cos^2(a)+ cot(a)*cos(a)
cot = cos/sin
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cos^2/sin^2 = cos^2 + cos^2/sin
1/sin^2 = 1 + 1/sin
1 = sin^2 + sin
sin^2 + sin - 1 = 0
*[invoke solve_quadratic_equation 1,1,-1]
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sin(a) =~ 0.618034
a =~ 38.17 degs (principal value)
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Not an identity.