C = ∫ 0 3 π [ 1 − sin 2 1 2 x 1 − cos 2 1 2 x + 1 ] d x If the value of 2 + 1 4 4 C is in the form a / b where a and b are positive coprime integers and enter a + b as your answer.
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anti solution - hats off
A bit of simplifying shows that C is the integral of sec 2 1 2 x which gives: [ 1 2 tan 1 2 x ] 0 3 π = 1 2 Therefore 2 + 1 4 4 1 2 = 2 5 / 1 2 and so the final answer is 3 7 .
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Anti-solution: We notice that the title is "Christmas is the Solution". Being too lazy to actually solve the problem, we recall that Christmas is on 12/25. The question asks for a+b, so we assume that {a, b} = {12, 25}. Adding results in the correct answer of 37, by chance.
Good solution: Using cos 2 x + sin 2 x = 1 , the fraction simplifies down to cos 2 x / 1 2 sin 2 x / 1 2 = tan 2 x / 1 2 . Using tan 2 x + 1 = s e c 2 x , we are left with the integral of sec 2 x / 1 2 , which evaluates to 1 2 tan x / 1 2 . Evaluating from 0 to 3 π results in the value 12. Substituting into the given format gives the fraction 1 2 2 5 , so a + b = 3 7 .