1 Press Ctrl-A ©G Dear2009 – Not to be sold/Free to use Area of Circles and Elipses Stage 6 - Year 12 General Mathematic (HSC)

2 Area of Circle Radius Area =  r 2 5 cm =  x 5 2 = 25  cm 2 (Exact) ≈ cm 2 (Approx) 2 decimal place End of Slide

3 60 o 5 cm Area of Sector r Area = x  r 2 ≈ 13.1 cm 2 (Approx) 1 decimal place  360  Area = x  x Fraction of the circle. Area of the circle. End of Slide

4 Area of an Annulus Area =  R 2 =  x 5 2 = 21  cm 2 (Exact) ≈ cm 2 (Approx) 2 decimal place R r -  r 2 5cm 2cm -  x 2 2 Annulus Grass Garden Area of Large circle. Area of small circle. End of Slide

5 3cm 4cm Area of an Ellipse Area =  ab =  x 3 = 12  cm 2 (Exact) ≈ 37.7 cm 2 (Approx) 1 decimal place x 4x 4 a b Drawing an Ellipse End of Show