Run to the right, but let go before sliding down the \ slope closest to the start. On falling, you hit the next / slope just below halfway down the level, then do a single jump up which should take you above the corner of the triangle and above the rocket. Fall down and to the right to land on the \ slope; do a running jump from that to the wall to your right while grabbing the switch, walljump to the wall above you on the left, walljump from that to the / slope on the right, run up it and perpendicular jump to the wall on your left and jump to the exit.