1. Formulae http://hench-maths.wikispaces.com

2. Perimeter Formulae for Polygons

3. Area of rectangle b=base h=height Area= bh Base is at RIGHT ANGLE to Height

4. Area of Square b=base Height=Base=b Area= b 2 A square is a rectangle with all equal sides Base=Height

5. Area of a Parralelogram Area= bh Base is at RIGHT ANGLE to Height

6. NameShapePerimeterArea SquareP=4bA=b 2 RectangleP=2b+2h =2(b+h) A=bh ParallelogramA=bh RhombusP=4bA=bh TrapeziumA=1/2(b 1 +b 2 ) Formulas for Quadrilaterals

7. Area of a triangle The area of a triangle is equal to half the area of the rectangle that can be drawn with the same base and height. base height The Area of the triangle can thus be calculated using the formula Area = ½ base x height or in algebraic form A= ½ bh

8. Examples 10cm 8cm 6cm 7cm Area =½ base X height = ½ x 10 x 8 = ½x80 =40 sq cm Area =½ base X height = ½ x 6 x 7 = ½x42 =21 sq cm

9. Diameter Radius centre What is the formula relating the circumference to the diameter ?

10. People knew that the circumference is about 3 times the diameter but they wanted to find out exactly. C = ? x d C ≈ 3 x d This means APPROXIMATELY EQUAL TO

11. How can we find the relationship between the circumference of a circle and its diameter?

12. Early Attempts Egyptian Scribe Ahmes. in 1650 B.C. said C≈3.16049 x d ArchimedesArchimedes, said C ≈3.1419 x d Fibonacci. In 1220 A.D. said C≈3.1418xd What is the value of the number that multiplies the diameter to give the circumference????

13. The exact value is…………… UNKNOWN!!

14. An approximation to π π≈3.141592653589793238462643383279502884 19716939937510582097494459230781640628 62089986280348253421170679821480865132 82306647093844609550582231725359408128 48111745028410270193852110555964462294 89549303819644288109756659334461284756 48233786783165271201909145648566923460 34861045432664821339360726024914127372 45870066063155881748815209209628292540 91715364367892590360011330530548820466 521384146951941511609................forever….

15. The Area and Perimeter of a Circle A circle is defined by its diameter or radius Diameter radius The perimeter or circumference of a circle is the distance around the outside The area of a circle is the space inside it The ratio of π (pi) π is an irrational number whose value to 15 decimal places is π = 3.14159265358979.... We usually say π≈3.14 The circumference is found using the formula C=π d or C= 2πr (since d=2r) The area is found using the formula A=πr 2

16. The Area and Perimeter of a Circle A circle is defined by its diameter or radius Diameter radius The perimeter or circumference of a circle is the distance around the outside The area of a circle is the space inside it The ratio of π (pi) π is an irrational number whose value to 15 decimal places is π = 3.14159265358979.... We usually say π≈3.14 The circumference is found using the formula C=π d or C= 2πr (since d=2r) The area is found using the formula C=πr 2