5.2.5 Circles, PT3 Focus Practice

Question 12: Amy will place a ball on top of a pillar in Diagram below. Table below shows the diameters of three balls X, Y and Z. Which ball X, Y or Z, can fit perfectly on the top of the pillar? Show the calculation to support Amy’s choice. Solution: Let the radius of the top of the pillar=r cm. O is the centre of the circle. In Δ OQR, r 2 = ( r−4 … Read more

5.2.4 Circles, PT3 Focus Practice

Question 10: Diagram below shows two quadrants, AOC and EOD with centre O. Sector AOB and sector BOC have the same area. Calculate the area, in cm2, of the coloured region. ( Use π= 22 7 ) Solution: Area of the sector AOB=Area of the sector BOC Therefore, ∠AOB=∠BOC = 90 o ÷2 = 45 o Area of the coloured region = 45 o 360 o × 22 7 × 16 … Read more

5.1b Circles

5.1.2 Circumference of a Circle    circumference=πd,      where d=diameter                            =2πr,     where r=radius                                    π(pi)= 22 7      or   3.142 Example: Calculate the circumference of a circle with a diameter of 14 cm. ( π= 22 7 ) Solution: Circumference=π× Diameter                       = 22 7 ×14                       =44 cm 5.1.3 Arc of a Circle The length of an arc of a circle is proportional to the angle … Read more

5.1a Circles

5.1a Circles   5.1.1 Parts of a Circle 1. A circle is set of points in a plane equidistant from a fixed point. 2. Parts of a circle: (a)    The centre, O, of a circle is a fixed point which is equidistant from all points on the circle. (b)   A sector is the region enclosed by two … Read more