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
