Tan α = 2, what degree is α equal to? You can't use the computer~

Tan α = 2, what degree is α equal to? You can't use the computer~

arctan2

If Tan (α + β) = 25, Tan (β - π 4) = 14, then Tan (α + π 4)=______ ．

Because α + π 4 = [(α + β) - (β - π 4)], and Tan (α + β) = 25, Tan (β - π 4) = 14, then according to the formula of tangent function of two angle difference, Tan (α + π 4) = Tan [(α + β) - (β - π 4)] = Tan (α + β) - Tan (β - π 4) 1 + Tan (α + β) Tan (β - π 4) = 25-141 + 25 × 14 = 322, so the answer is 322

∫ DX / (XLN & # 178; x) = speed of the gods

∫dx/（xln²x）=∫d(lnx)/ln²x=-1/lnx+C