American Accent Training phần 5

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American Accent Training phần 5 5658 SAT2006[04](fin).qx 11/21/05 6:44 PM Page 133 – THE SAT MATH SECTION – 45-45-90 Right Triangles 30-60-90 Triangles In a right triangle with the other angles measuring 30° and 60°: 45° The leg opposite the 30-degree angle is half the ■ length of the hypotenuse. (And, therefore, the 45° hypotenuse is two times the length of the leg opposite the 30-degree angle.) The leg opposite the 60 degree angle is 3 times ■ A right triangle with two angles each measuring 45° is the length of the other leg. called an isosceles right triangle. In an isosceles right triangle: 60° The length of the hypotenuse is 2 multiplied by ■ 2s the length of one of the legs of the triangle. s 2 The length of each leg is 2 multiplied by the ■ length of the hypotenuse. 30° s√¯¯¯ 3 Example: 10 x 60° x 7 y 10 2 2 10 × x=y= = =5 2 2 30° 2 1 y x = 2 × 7 = 14 and y = 7 3 133 5658 SAT2006[04](fin).qx 11/21/05 6:44 PM Page 134 – THE SAT MATH SECTION – Triangle Trigonometry Circles A circle is a closed figure in which each point of the cir- There are special ratios we can use with right triangles. cle is the same distance from a fixed point called the They are based on the trigonometric functions called ...