integration question?

2008-01-15 8:31 pm
find the area under the curve 3sin2x between x=0 ,x=180/2 ?

回答 (2)

2008-01-16 11:30 pm
✔ 最佳答案
π/2
∫3sin2x dx
0
π/2
=3∫sin2x dx
0
π/2
=[-3/2(cos2x)+C]
0
=--3/2 cos(2 x (π/2))-(-3/2)cos 0

= -3/2 cosπ-(-3/2)cos 0

= -3/2(-1) -(-3/2)(1)

= 3/2 + 3/2

= 3
2008-01-15 9:39 pm
∫3sin2x dx
=3∫sin2x dx
=(-3/2)(cos2x)+C
So the area under the curve 3sin2x between x=0 ,x=π/2
=(-3/2)(cosπ)-(-3/2)(cos0)
=(3/2)+(3/2)
=3


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