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Answer:
The value of Cos 15 is 0.96592582, it can also be written as Cos (45-30) º. Cos 15 º can be calculated in few ways, one of them being Cos 15 º = Cos (45-30) º and the other being Cos 2θ=2Cos2θ-1, In this if Ɵ = 15 º then Cos 15 º can be calculated by using Cos 30 º using the trigonometric table. We will be using both the methods to find the value of Cos 15 º
Using Cos 15°=Cos (45-30)°: If we solve this equation using trigonometry rules we will get;
Cos 45-30°=Cos45°*Cos30°+Sin45°*Sin30°
As we know the values of Cos45, Cos30, Sin45, Sin30 let us substitute them with their respective values;
After rationalising √(√3+2)/2 we can come to conclusion that Cos15°= √3+1/2√2. We can also write the value of Cos15 in terms of decimal which will be approximately 0.96592582.
Hence the value of Cos15 can either be Cos15°= √3+1/2√2 or 0.96592582.
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