  We get a local existence result in $H^s$ with $s>3/2$ for second order
quasilinear wave equation with radial initial data in 2+1 dimensions, based on
an improvement of Strichartz estimate in the radial case. Moreover, we get the
corresponding local well-posed result for semilinear wave equation. The
required index of regularity here is 1/4 less than the index 7/4, which is
essentially sharp in general.
