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AMSCO'S Geometry. New York - Rye High School

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Pythagorean Theorem 519EXAMPLE 3In right triangle ABC, the length of the hypotenuse,AB, is 6 centimeters and the length of one leg is 3 centimeters.Find the length of the other leg.BSolutiona 2 1 b 2 5 c 2a 2 1 (3) 2 5 (6) 2a 2 1 9 5 36a 2 5 27a 5 "27 5 "9 ? 3 5 3"3Answer6 cmC3 cmANote: The measure of one leg is one-half the measure of the hypotenuse and"3the length of the other leg is 2 times the length of the hypotenuse. Therefore,this triangle is a 30-60-degree right triangle. We can use a calculator to verifythis.oppRecall that tan A = adj 5 AC BC 5 3"33 5 "3. Use a graphing calculator tofind the measure of A.ENTER:2ndTAN 12nd¯ENTERThe calculator will return 60 as mA. Therefore, mB 30.3ExercisesWriting About Mathematics1. Ira said that if the lengths of the sides of an obtuse triangle ABC are a, b, and c with copposite the obtuse angle, then c 2 a 2 b 2 . Do you agree with Ira? Explain why or whynot. (Hint: Make use of the altitude from one of the acute angles.)2. Sean said that if the measures of the diagonals of a parallelogram are 6 and 8 and the measureof one side of the parallelogram is 5 then the parallelogram is a rhombus. Do you agreewith Sean? Explain why or why not.Developing SkillsIn 3–8, in each case the lengths of three sides of a triangle are given. Tell whether each triangle is aright triangle.3. 6, 8, 10 4. 7, 8, 12 5. 5, 7, 8 6. 15, 36, 39 7. 14, 48, 50 8. 2, 2"3, 4

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