Evaluate cos (pi/3)

we have to find the value of cos(pi/3)

Solution

We know that pi=180 degrees

cos(pi/3)= cos (180/3)= cos 60

Hence we can find cos 60 value using sin 60

We know that

90° – 30° = 60° ———– (1)

From the trigonometry formula,

sin (90° – a) = cos a

We can find the value of cos 60

We can write it as

Sin (90° – 60°) = cos 60°

Sin 30° = cos 60° ——(2)

We know that the value of sin 30 degrees is ½

Now substitute the value in (2)

½ = cos 60°

Therefore, the value of cos 60 degrees is ½

Cos 60° = 1/2

Hence cos (pi/3) = 1/2

Answer

cos (pi/3) = 1/2

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