SSC CGL Tier II 25 Oct 2015 Paper 1

(1) Expression = (cot 41° . cot 49°) . (cot 42° . cot 48°) (cot 43° . cot 47°) . (cot 44° . cot 46°) . cot 45°
= cot 41° . tan (90° – 49°) . cot 42° . tan (90° – 48°) . cot 43° . tan (90° – 47°) . cot 44° . tan (90° – 46°).1
= (cot 41° . tan 41°) (cot 42° . tan 42°) . (cot 43° . tan 43°). (cot 44° . tan 44°) . 1 = 1
[∵ tan (90° – θ) = cotθ; tanθ. cotθ = 1]