BLOCK towards right. For the condition of equilibrium \[mg\sin \theta =ma\COS \theta \] Þ \[a=\frac{g\sin \theta }{\cos \theta }\] \[\THEREFORE \] Force exerted by the WEDGE on the block \[R=mg\cos \theta +ma\sin \theta \] R\[=mg\cos \theta +m\left( \frac{g\sin \theta }{\cos \theta } \right)\sin \theta \]\[=\frac{mg({{\cos }^{2}}\theta +{{\sin }^{2}}\theta )}{\cos \theta }\] R\[=\frac{mg}{\cos \theta }\]