求∫secx rt.

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求∫secx rt.

求∫secx rt.
求∫secx
rt.

求∫secx rt.
sec x = 1/cos x
∫secx dx = ∫dx/cos x=∫cosx/(cosx)^2 dx = ∫ 1/(cosx)^2 d(sinx)
= ∫d(sinx)/(1-(sin x)^2) = -1/2*[∫ 1/(sinx-1) d(sinx) - ∫1/(sinx+1) d(sinx)]
= -1/2*ln|(sinx-1)/(sinx+1)|+C

原式=∫cosx/cos²xdx
=∫dsinx/(1-sin²x)
=1/2*∫[1/1+sinx)-1/(sinx-1)]dsinx
=1/2*[ln|1+sinx|-ln|sinx-1|]+C
=1/2*ln[(1+sinx)/(1-sinx)]+C
上下除cosx
=1/2*ln[(secx+tanx)/(srcx-tanx)]+C