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2 Types of Triangles Types by Length Equilateral Isosceles Scalene Types by Angle Equilateral Right Obtuse Acute Equilateral Right Isosceles Scalene Equilateral Obtuse Acute
6/22/20163 Right Triangles Legs Shorter sides of triangle Hypotenuse Longer side of triangle Side opposite right angle Hypotenuse leg
6/22/20164 Pythagoras Born: about 569 BC in Samos, Iona, Greece Died: about 475 BC Greek philosopher Mathematician Most Known For: Sum of Angles of a Triangle Pythagorean Theorem Constructing Figures of a Given Area and Geometric Algebra Discovery of Irrational #s The 5 Regular Solids Whole Number Ratios of Consonant Intervals Musica Mundana
6/22/20165 Pythagorean Theorem If the triangle had a right angle (90°)... ... and you made a square on each of the three sides, then... ... the biggest square had the exact same area as the other two squares put together! Proof of the Pythagorean Theorem
6/22/20166 Pythagorean Example The formal equation is: a 2 + b 2 = c 2 “a” and “b” are the two legs “c” is the hypotenuse TRY THIS: a = 3 b = 4 c = 5 a 2 + b 2 = c = 5 2 Calculating this becomes: = 25 yes, it works !
6/22/20167 More Examples Find c in : a 2 + b 2 = c 2 where a = 5 and b = = c = 169 c 2 = 169 c = √169 c = 13 Find b in : a 2 + b 2 = c 2 where a = 9 and c = b 2 = b 2 = 225 Take 81 from both sides b 2 = 144 b = √144 b = 12
6/22/20168 Pythagorean Triples A "Pythagorean Triple“ a set of three numbers a,b,c such that a²+b²=c². Pythagoras proved that the sides of a right triangle have this relationship He then went crazy after discovering that the sides of a right triangle aren't always rational.
6/22/20169 Real - Life Application TV screens & computer monitors are measured on the diagonal
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