5. Suppose that u is a harmonic function in the disk D = {r

I will upvote. clear explanation plz

Extracted text: 5. Suppose that u is a harmonic function in the disk D = {r< 2}="" and="" that="" u="sin" 30="" –="" 2="" cos="" 30="" +4="" for="" r="2." (a)="" find="" the="" maximum="" and="" minimum="" values="" of="" u="" in="" d.="" (b)="" calculate="" the="" value="" of="" u="" at="" the="" origin.="" (c)="" find="">