A square is a shape with four equal sides Example: All its angles are ninety degrees
Another meaning of square is to square a number The square of a number = the number times itself 1 squared = 1 x 1 = 1 2 squared = 2 x 2 = 4 3 squared = 3 x 3 = 9 4 squared = 4 x 4 = 16 5 squared = 5 x 5 = 25
The area of a square with side 4 cm is 16 square cm
The area of a square with side 3 cm is 9 square cm
The area of a square with side 5 cm is 25 square cm
For ANY right angled triangle the square on the hypotenuse equals the sum of the squares on the other two sides. a b c a 2 + b 2 = c 2 a b c a b c = the hypotenuse
Blue area = c x c = c squared = c 2
Total = Blue + Red Total – Red = Blue = c 2
Blue = axa + bxb = a 2 + b 2 = c 2
Challenge: i) Find another Pythagorean triad (other than 3,4,5 with all three numbers under 20 ii) How many triads are there where all three numbers are under 100?
1 1 x X 2 = 2 because = = = 2.25 (too big) = (too small) = 1.69 (too small) = 1.96 (too small) = ( …) 2 = 2 √2 is an irrational number It is NOT a fraction or a repeating decimal
History Donald 50 secs to 5min 39 secshttp://youtu.be/b8DrYz_cKR0 Pythagorean triads (start at 3 min 45 secs) Proof of Pythagoras’ theorem (start at 1 min 52 secs) Another look at the same proof (60 seconds) Funny film