- #1
beborche
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Homework Statement
Write arctan8 + arctan11 as an expression containing max one term with arctan.
Homework Equations
tan(u+v) = [itex]\frac{tanu+tanv}{1-tanutanv}[/itex]
arctan(tanx) = x
The Attempt at a Solution
u = arctan8, v = arctan11
tan(u+v) = [itex]\frac{tanu+tanv}{1-tanutanv}[/itex] = [itex]\frac{8+11}{1-8*11}[/itex] = -(19/87) = tan(arctan8 + arctan11)
arctan(tan(arctan8 + arctan11)) = arctan(-(19/87)) = arctan8 + arctan11
arctan8 + arctan11 = arctan(-/19/87)) = -arctan(19/87)
But (arctan8 + arctan11) > 0 and -arctan(19/87) < 0
Where have I gone wrong?
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