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Exercise. Solve x 2 = 4. x = ± 2. Exercise. Solve x 2 = – 4. no real solution. Exercise. Solve √ x = 4. x = 16. Exercise. Solve √ x = – 4. no real solution. Exercise. Solve √ – x = 4. x = – 16. hypotenuse. leg. leg. 25 square units. 9 square units. 3. 5. 4.
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Exercise Solve x2 = 4. x = ± 2
Exercise Solve x2 = –4. no real solution
Exercise Solve √x = 4. x = 16
Exercise Solve √x = –4. no real solution
Exercise Solve √–x = 4. x = –16
hypotenuse leg leg
25 square units 9 square units 3 5 4 16 square units
3 5 4 25 square units 9 square units += 16 square units
42 32 52 += 16 9 25
The Pythagorean Theorem If the hypotenuse of a right triangle has length c, and the legs have lengths a and b, then a2 + b2 = c2.
√c2 = √289 Example 1 Find the hypotenuse of a right triangle with legs of 8 and 15. c2 = a2 + b2 c2 = 289 c2 = 82 + 152 c2 = 64 + 225 c = 17
√c2 = √85 c = √85 ≈ 9.2 Example 2 Find the hypotenuse of a right triangle with legs of 6 and 7. c2 = a2 + b2 c2 = 85 c2 = 62 + 72 c2 = 36 + 49
Example Find the hypotenuse of a right triangle with legs of 9 and 12. 15
Example Find the hypotenuse of a right triangle with legs of and . 12 √32 1
√2 Example Find the hypotenuse of a right triangle with legs of 1 and 1.
a = √207 ≈ 14.4 Example 3 Find the leg of a right triangle whose hypotenuse is 16 and other leg is 7. a2 + 72 = 162 a2 + 49 = 256 a2 + 49 – 49 = 256 – 49 a2 = 207
Example Find the length of a leg of a right triangle whose hypotenuse is 39 and whose other leg is 15. 36
√300 ≈ 17.3 Example Find the length of a leg of a right triangle whose hypotenuse is 20 and whose other leg is 10.
Converse The converse is the statement resulting when the “if” part and the “then” part of a conditional statement are switched.
Converse of the Pythagorean Theorem If a triangle has sides a, b, and c, such that a2 + b2 = c2, then the triangle is a right triangle.
Example 4 Determine whether a triangle with sides of 12, 35, and 37 is a right triangle. a2 + b2 = c2 yes 122 + 352 = 372 144 + 1,225 = 1,369 1,369 = 1,369
Example 5 Determine whether a triangle with sides of 8, 12, and 14 is a right triangle. a2 + b2 = c2 no 82 + 122 = 142 64 + 144 = 196 208 ≠ 196
Example Determine whether a triangle with sides of 15, 18, and 22 is a right triangle. no; 152 + 182 ≠ 222
Example Determine whether a triangle with sides of 16, 30, and 34 is a right triangle. yes; 162 + 302 = 1,156 = 342
Exercise A 16 ft. ladder leans up against the side of a building. If the base of the ladder is 4 ft. from the base of the building, how high up the side of the building will the ladder reach? 15.5 ft.
Exercise A 200 ft. tower is braced to the ground by a cable, from a point 150 ft. above the ground to a point 87 ft. from the base of the tower. How long is the cable? 173.4 ft.
Exercise The distance between bases on a baseball diamond is 90 ft. How far is it from home plate to second base? 127.3 ft.
Exercise An opening for a window is 23” wide, 54” tall, and 60” diagonally. Is the opening “square”; that is, do the height and width form a right angle? no