Cosec A + cot A - 1 / cot A - cosec A + 1 we know that,cosec ² A - cot ² A = 1 substituting this in the numerator cosec A + cot A -(cosec ² A - cot ² A) / (cot A - cosec A + 1) x²-y²= (x+y)(x-y) cosec A + cot A - (cosec A + cot A) (cosec A - cot A) / (cot A - cosec A + 1) taking common (cosec A + cot A)(1-cosec A + cot A) / (cot A - cosec A + 1) cancelling like terms in numerator and denominator we are left with cosec A + cot A = 1/sin A + cos A/sin A = (1+cos A) / sin A