表达式4: "X" left parenthesis, "l" , right parenthesis equals Start sum from "i" equals 0 to floor left parenthesis, "l" , right parenthesis , end sum, sine left parenthesis, "a" left parenthesis, "i" , right parenthesis , right parenthesis plus mod left parenthesis, "l" , 1 , right parenthesis sine left parenthesis, "a" left parenthesis, floor left parenthesis, "l" , right parenthesis plus 1 , right parenthesis , right parenthesisXl=floorl∑i=0sinai+modl,1sinafloorl+1
4
表达式5: "Y" left parenthesis, "l" , right parenthesis equals Start sum from "i" equals 0 to floor left parenthesis, "l" , right parenthesis , end sum, cosine left parenthesis, "a" left parenthesis, "i" , right parenthesis , right parenthesis plus mod left parenthesis, "l" , 1 , right parenthesis cosine left parenthesis, "a" left parenthesis, floor left parenthesis, "l" , right parenthesis plus 1 , right parenthesis , right parenthesisYl=floorl∑i=0cosai+modl,1cosafloorl+1
5
表达式6: left parenthesis, "X" left parenthesis, "t" , right parenthesis , "Y" left parenthesis, "t" , right parenthesis , right parenthesisXt,Yt
定义域t最小值： 00
less than or equal to "t" less than or equal to≤t≤
定义域t最大值： 2121
6
表达式7: "r" less than or equal to 20r≤20
00
定义域\theta最小值：
less than or equal to theta less than or equal to≤θ≤
