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## Homework Statement

dr/d∅+rtan∅=cos∅

μ(∅)=exp[∫tan∅]

μ∅=exp[-ln[cos∅]=-cos∅

-cos∅(dr/d∅)-rtan∅cos∅=-cos^2∅

dr/d∅[-rcos∅]=-cos^2∅

rcos∅=∫cos^2∅

changed cos^2∅ to 1/2+1/2cos2∅

rcos∅=1/2∅ + 1/4 sin2∅+c

the books answer is not even close to mine they have r=(∅+c)cos∅

Where did I go wrong?