Frédéric Chopin's set of twenty-four Preludes, Op. 28, is a treasure trove of miniature masterpieces, each exploring a unique mood and technical challenge. Among them, the seventh—the famous Prelude in A major—stands out as a jewel of lyrical simplicity and a perfect piece for the intermediate pianist to explore.

A key signature is the sharp signs next to the clef. In this case we have F sharp, C sharp and G sharp. If you need help here please see the key signatures blog. The tonic triad is the 1st , 3rd and 5th note of the scale. When there is no key signature this triad requires an sharp sign in front of the C to make it a C sharp. It does not need a F sharp or a G sharp as there is no F or C in the triad to raise by a semitone.