60 likes | 88 Views
Shape and Space. Circles. Formula for the area of a circle. We can find the area of a circle using the formula. Area of a circle = π × r × r. or. radius. Area of a circle = π r 2. The circumference of a circle. Use π = 3.14 to find the area of this circle. 4 cm. A = π r 2.
E N D
Shape and Space Circles
Formula for the area of a circle We can find the area of a circle using the formula Area of a circle = π×r×r or radius Area of a circle = πr2
The circumference of a circle Use π = 3.14 to find the area of this circle. 4 cm A = πr2 = 3.14 × 4 × 4 = 50.24 cm2
Finding the area given the diameter d r = 2 πd2 A = 4 The radius of a circle is half of its radius, or We can substitute this into the formula A = πr2 to give us a formula to find the area of a circle given its diameter.
The area of a circle 2 cm 10 m 78 cm 23 mm Use π = 3.14 to find the area of the following circles: A = πr2 A = πr2 = 3.14 × 22 = 3.14 × 52 = 12.56 cm2 = 78.5 m2 A = πr2 A = πr2 = 3.14 × 232 = 3.14 × 392 = 1661.06 mm2 = 4775.94 cm2
Find the area of this shape Use π = 3.14 to find area of this shape. The area of this shape is made up of the area of a circle of diameter 13 cm and the area of a rectangle of width 6 cm and length 13 cm. Area of circle = 3.14 × 6.52 13 cm 6 cm = 132.665 cm2 Area of rectangle = 6 × 13 = 78 cm2 Total area = 132.665 + 78 = 210.665 cm2