The value of : (a18+a−18)(a18−a−18)(a14+a−14)(a12+a−12) is -
Using (a+b)(a−b)=a2−b2,we get :
(a18+a−18)(a18−a−18)(a14+a−14)(a12+a−12)
=(a14−a−14)(a14+a−14)(a12+a−12)
= (a12−a−12)(a12+a−12)=(a1−a−1).
(1 + tan A + sec A)(1 + cot A − cosec A) = ? (a) 1 (b) 0 (c) 2 (d) 4