A and B are acute angles with tanA = 1/2 and tanB = 1/3. Then A + B equals:

tan(A + B) = (tanA + tanB)/(1 − tanA·tanB) = (1/2 + 1/3)/(1 − 1/6) = (5/6)/(5/6) = 1, and since A ≈ 26.6° and B ≈ 18.4°, the sum is the acute angle 45°. Adding the tangents alone gives 5/6, whose angle is about 39.8° — no listed value; and the pair would be complementary (90°) only if tanA·tanB = 1, whereas here that product is 1/6.