Evaluate : ∫(1−cosx)(2−cosx)sinxdxAnswer: log∣1−cosx∣−log∣2−cosx∣+CSolutionPut t=cosx, dt=−sinxdx:−∫(1−t)(2−t)dt.Partial fractions give (1−t)(2−t)1=1−t1−2−t1, so−∫[1−t1−2−t1]dt=log∣1−t∣−log∣2−t∣+C.Restoring t=cosx,log∣1−cosx∣−log∣2−cosx∣+CCBSE Class 12 Board · 2007 · Subjective