→ goshfju:其實看不太懂你的題目 218.167.72.210 11/06 01:15
→ triumph323:微分兩次 然後 θ帶二 題目好像是這樣묠203.121.241.103 11/06 01:35
→ royalksdmc:...微一次變-πsin(θπ) 61.57.123.56 11/06 01:48
→ royalksdmc:第二次變-π^2cos(θπ), cos(2π)=-1 61.57.123.56 11/06 01:48
→ royalksdmc:算錯了2π=1 61.57.123.56 11/06 01:50
→ triumph323:我好像少打 cos(θπ)^-2 d/dθ203.121.241.103 11/06 16:50