乾 has two readings: qián (the trigram for heaven, as in 乾坤) and gān (dry, the traditional form of 干). In simplified Chinese, 干 replaced 乾 for the 'dry' meaning, but 乾 is still used for the trigram meaning.
Left side depicts the sun rising through plants - a morning scene evoking drying heat and the bright forces of yang. Same graphic anchors 韩, 朝, 翰, 斡. In 乾 it carries the dry/heaven sense, fitting the trigram pure yang. Indexed under Kangxi #5 乙 by tradition; no visible 乙-element survives.
Right 乞 supplies the sound, with the regular qǐ to qián vowel/tone shift typical of older phono-semantic pairings. Pure phonetic role here - the begging sense plays no part in the meaning. The pictograph traces back to a person bent forward with arm outstretched.
Filed under radical 乙 (yǐ, #5) by convention. 乙 is not a separate component in 乾, so no strokes are highlighted.
