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10.5 – The Pythagorean 10.5 – The Pythagorean Theorem Theorem

10.5 – The Pythagorean Theorem. leg legleg hypotenuse hypotenuse leg legleg

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10.5 – The Pythagorean Theorem10.5 – The Pythagorean Theorem

legleg

legleg

hypotenusehypotenuse

legleg

legleg

hypotenusehypotenuse

legleg

legleg

Pythagorean TheoremPythagorean Theorem: For a right triangle with legs : For a right triangle with legs aa and and bb and hypotenuse and hypotenuse cc, ,

then then aa22 + + bb22 = = cc22, where , where aa is the is the smaller of the two legs.smaller of the two legs.

Ex. 1Ex. 1 Find the length of the missing side. Find the length of the missing side.

a 25a 25

1010

Ex. 1Ex. 1 Find the length of the missing side. Find the length of the missing side.

a 25a 25

1010

aa22 + + bb22 = = cc22

Ex. 1Ex. 1 Find the length of the missing side. Find the length of the missing side.

a 25a 25

1010

aa22 + + bb22 = = cc22

aa22 + (10) + (10)22 = (25) = (25)22

Ex. 1Ex. 1 Find the length of the missing side. Find the length of the missing side.

a 25a 25

1010

aa22 + + bb22 = = cc22

aa22 + (10) + (10)22 = (25) = (25)22

aa22 + 100 = 625 + 100 = 625

Ex. 1Ex. 1 Find the length of the missing side. Find the length of the missing side.

a 25a 25

1010

aa22 + + bb22 = = cc22

aa22 + (10) + (10)22 = (25) = (25)22

aa22 + 100 = 625 + 100 = 625

aa22 = 525 = 525

Ex. 1Ex. 1 Find the length of the missing side. Find the length of the missing side.

a 25a 25

1010

aa22 + + bb22 = = cc22

aa22 + (10) + (10)22 = (25) = (25)22

aa22 + 100 = 625 + 100 = 625

aa22 = 525 = 525

aa ≈ 22.91 ≈ 22.91

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Shorter lengths Shorter lengths mustmust be the be the legs. legs.

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Shorter lengths Shorter lengths mustmust be the be the legs. legs.

So, So, aa22 + + bb22 = = cc22

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Shorter lengths Shorter lengths mustmust be the be the legs. legs.

So, So, aa22 + + bb22 = = cc22

(20)(20)22 + (21) + (21)22 = (29) = (29)22

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Shorter lengths Shorter lengths mustmust be the be the legs. legs.

So, So, aa22 + + bb22 = = cc22

(20)(20)22 + (21) + (21)22 = (29) = (29)22

400 + 441 = 841400 + 441 = 841

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Shorter lengths Shorter lengths mustmust be the be the legs. legs.

So, So, aa22 + + bb22 = = cc22

(20)(20)22 + (21) + (21)22 = (29) = (29)22

400 + 441 = 841400 + 441 = 841

841 = 841 841 = 841

Ex. 2Ex. 2 Determine whether the following side Determine whether the following side measures form right triangles.measures form right triangles.

a. 20, 21, 29a. 20, 21, 29

Shorter lengths Shorter lengths mustmust be the legs. be the legs.

So, So, aa22 + + bb22 = = cc22

(20)(20)22 + (21) + (21)22 = (29) = (29)22

400 + 441 = 841400 + 441 = 841

841 = 841 841 = 841

, so they form a rt. triangle!, so they form a rt. triangle!