how to find the area of a sector when the radius is 8 and you leave it in terms of pi

you would have to know the central angle of the sector.

Suppose it is Ø

then area of whole circle = 64π
area of sector with central angle Ø/64π = Ø/360°

area of sector = 64π(Ø°)/360°

e.g. if the central angle is 60°
area of sector = 64π(60)/(360) = 32π/3