Need help with trigonometry

1. A chord PQ of a circle centre O, radius 10cm, subtends an angle of $\displaystyle \pi$/4 at the centre of the circle. Find the length of the major arc PQ and the area of the minor segment cut off by the chord.

2. The lengths of the side of a triangle are 10cm, x cm and (x-2)cm. The side of length (x-2)cm is opposite an angle of 60 degrees. Find x.

3. The area of a sector of a circle, diameter 7cm is 18.375cm squared. Find, without using a calculator, the length of the arc of the sector.

thanks in advance