6 ORDER OF OPERATIONS
To work out the area of a circle, the radius is multiplied by itself and then this is multiplied by p . p is just a symbol for 3·1415926535897932…..
Algebraically the formula is written
To get the correct answer the radius must be squared before it is multiplied by p and so we adopt the rule that regardless of the order in which a formula is written, powers, such as 2, 3, are worked out before multiplication.
| Area of
circle of radius 7cm
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6A Work out the area of each of these circles.
1. Radius 5cm 2. Radius 9cm 3. Radius 70cm
To work out the area of a sector of a circle, it is necessary to develop the formula for the area of a circle.
Area of quarter circle
6B For each of these sectors, write down a suitable formula to work out its area and use your formula to work out each area.
