[理工] [工數]-拉式轉換
1.
3
-1 s
L [ ---------- ]
4 4
s + 4a
3
s
= --------------------
2 2 2 2
(s + 2a ) - (2as)
如何變成
1 at 1 -at
---e cosat + ---e cosat
3 2
2.
周易寫真密集 p 4-53 習題8
的拋物線方程式怎麼列..@@
3.
-1 s
L [ --------- ]
2 2
(s - 1)
答案是
t
---sinht
2
我是這樣算..
-1 1 -1 s
L [ ------- ] * L [ -------- ]
2 2
s - 1 s - 1
= sin(-t)* cos(-t)
= sint*-cost
t
= -∫ sinαcoa(t-α) dα
0
-1 t
= ---[ ∫ sint + sin(-t+2α) dα
2 0
-1 1 1
= ---(tsint - --- - ---cost)
2 2 2
哪一步錯了阿 還是第一步就錯了..
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