first of all, the name of the Greek letter is pi not pie.
cos 5π/12 = (√3-1) / 2√2
cos2π/9 cosπ/18 + sin2π/9 sinπ/18 = cos(2π/9 - π/18) = cos π/6 = √3/2
Hi i have two questions:
what is the exact value of cos 5(pie)/12?
what is the exact value of cos2(pie)/9 cos(pie)/18 + sin2(pie)/9 sin(pie)/18?
thank you
1 answer