  We present an angular analysis of the $B^{+}\rightarrow K^{\ast+}(\rightarrow
K_{S}^{0}\pi^{+})\mu^{+}\mu^{-}$ decay using 9$\,\mbox{fb}^{-1}$ of $pp$
collision data collected with the LHCb experiment. For the first time, the full
set of CP-averaged angular observables is measured in intervals of the dimuon
invariant mass squared. Local deviations from Standard Model predictions are
observed, similar to those in previous LHCb analyses of the isospin-partner
$B^{0}\rightarrow K^{\ast0}\mu^{+}\mu^{-}$ decay. The global tension is
dependent on which effective couplings are considered and on the choice of
theory nuisance parameters.
