Complex sentence: For example, objects appear to grow larger or smaller depending on whether the observer moves towards or away from the object because the angle subtended by the object to the observer gets bigger as the observer gets closer and smaller as the observer recedes.
Split into simpler sentences: For example, objects appear to grow larger or smaller depending on whether the observer moves towards or away from the object. This is because the angle subtended by the object to the observer gets bigger as the observer gets closer, and smaller as the observer recedes.