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问题: 大学作业(12)

求不定积分

∫1/(a^2*sin^2 x +b^2*cos^2 x) dx

解答:

解:∫1/(a^2*sin^2x+b^2*cos^2x)dx
=∫1/{[(a/b)tanx]^2+1}*[1/(b^2*cos^2 x)]dx
=[1/(ab)]*∫1/{[(a/b)tanx]^2+1}*d[(a/b)tanx]
=[1/(ab)]* arctan[(a/b)tanx]+C