V = area of cross-section x length
= (7x3) x 2
= 42 unit^3
Q to R - cosine rule comes to mind
PQ is 8mm (radius along with PR)
QR = the square root of:
8^2 + 8^2 - 2 x 8 x 8 x cos120 = 8root 3
Or 13.8564....
(root means square root)
Thus, QR = 13.86mm
A = 120/360 x 3.14 x 8 x 8
= 66.9866....
Area of sector is 67 to the nearest mm^2
Hope this helps!
