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10.5 – The Pythagorean Theorem. leg leg. hypotenuse leg leg. hypotenuse leg leg
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leg leg
hypotenuse leg leg
hypotenuse leg leg Pythagorean Theorem: For a right triangle with legs a and b and hypotenuse c, then a2 + b2 = c2, where a is the smaller of the two legs.
Ex. 1 Find the length of the missing side. a 25 10 a2 + b2 = c2
Ex. 1 Find the length of the missing side. a 25 10 a2 + b2 = c2 a2 + (10)2 = (25)2
Ex. 1 Find the length of the missing side. a 25 10 a2 + b2 = c2 a2 + (10)2 = (25)2 a2 + 100 = 625
Ex. 1 Find the length of the missing side. a 25 10 a2 + b2 = c2 a2 + (10)2 = (25)2 a2 + 100 = 625 a2 = 525
Ex. 1 Find the length of the missing side. a 25 10 a2 + b2 = c2 a2 + (10)2 = (25)2 a2 + 100 = 625 a2 = 525 a ≈ 22.91
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29 Shorter lengths must be the legs.
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29 Shorter lengths must be the legs. So, a2 + b2 = c2
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29 Shorter lengths must be the legs. So, a2 + b2 = c2 (20)2 + (21)2 = (29)2
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29 Shorter lengths must be the legs. So, a2 + b2 = c2 (20)2 + (21)2 = (29)2 400 + 441 = 841
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29 Shorter lengths must be the legs. So, a2 + b2 = c2 (20)2 + (21)2 = (29)2 400 + 441 = 841 841 = 841
Ex. 2 Determine whether the following side measures form right triangles. a. 20, 21, 29 Shorter lengths must be the legs. So, a2 + b2 = c2 (20)2 + (21)2 = (29)2 400 + 441 = 841 841 = 841 , so they form a rt. triangle!