表达式2: "r" equals tau cosine left parenthesis, StartFraction, left parenthesis, StartAbsoluteValue, "n" , EndAbsoluteValue ! theta , right parenthesis Over "n" , EndFraction , right parenthesis 有图表。r=τcosn!θn
定义域\theta最小值: negative tau−τ
less than or equal to theta less than or equal to≤θ≤