表达式18: left parenthesis, "M" Subscript, 1 , Baseline plus "R" cos "t" , "M" Subscript, 2 , Baseline plus "R" sin "t" , right parenthesisM1+Rcost,M2+Rsint
定义域t最小值： negative 90−90
less than or equal to "t" less than or equal to≤t≤
定义域t最大值： 9090
18
表达式19: polygon left parenthesis, "A" , "B" , "C" , right parenthesispolygonA,B,C
19
表达式20: polygon left parenthesis, "B" , "M" , right parenthesispolygonB,M
