In the circle, O is the centre and AB is a diameter. a) work out the size of angle a
b) work out the size of angle b

He expression 2(l + w) is used to calculate the perimeter of a rectangle, where l is length and w is width. if the length is fraction 2 over 3 unit and the width is fraction 1 over 3 unit, what is the perimeter of the rectangle in units? fraction 2 over 3 unit 1 unit 1fraction 2 over 3 units 2 units

Ineed to know the answer right now! !

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?