a
\(P = \left( {mg\sin \theta  + \mu mg\cos \theta } \right)V\)

\( = \left( {1000 \times 9.8 \times \frac{1}{{\sqrt 5 }} + \frac{1}{{\sqrt 3 }} \times 1000 \times 9.8 \times \frac{2}{{\sqrt 5 }}} \right) \times 36 \times \frac{5}{{18}} = 94.4 \times {10^3}W\)

\(\tan \theta  = \frac{1}{2}\cos \theta  = \frac{2}{{\sqrt 5 }}\sin \theta  = \frac{1}{{\sqrt 5 }}\)