Are large passenger aircraft steered during taxi by changing the angle of the front landing gear?
During taxiing aircraft turn using their nose wheel. 

The nose wheel is usually hydraulically controlled. The pilot operates it through a tiller. The nose gear can rotate usually quite far, sometimes to almost 90 degrees. 

At high speeds, directional control is achieved using the rudder pedals. The nose gear is often linked to the rudder pedals, however the maximum rotation is limited. The nose gear steering does not exactly match to the the rudder steering at all speeds. At low speeds the rudder is ineffective so the nose wheel steering is dominant. For sharp turns the tiller is always used because of the limited rotation by the pedals.  





A320 Nose wheel tiller





B747-400 Nose wheel tiller