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1)

The value of  cos(12cos118) is equal to 


A) -3/4

B) 3/4

C) 1/16

D) 1/4

Answer:

Option B

Explanation:

Let  cos118=θ,where0<θ<π2

 12cos118=12θ,

cos(12cos118)=cos12θ,

Now, cos118=θcosθ=18

2cos2θ21=18

cos2θ2=916cosθ2=34

[0<θ2<π4,socosθ234]