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adj. to W. adj. to U. =. =. hyp. hyp. UV. 18. WV. 24. =. =. =. =. 3. 30. UW. UW. 30. =. 5. 4. =. 5. EXAMPLE 2. Find cosine ratios. Find cos U and cos W . Write each answer as a fraction and as a decimal. SOLUTION. cos U. = 0.6000. cos W. = 0.8000.
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adj. to W adj. to U = = hyp hyp UV 18 WV 24 = = = = 3 30 UW UW 30 = 5 4 = 5 EXAMPLE 2 Find cosine ratios Find cosU and cosW. Write each answer as a fraction and as a decimal. SOLUTION cosU = 0.6000 cosW = 0.8000
DOG RUN You want to string cable to make a dog run from two corners of a building, as shown in the diagram. Write and solve a proportion using a trigonometric ratio to approximate the length of cable you will need. EXAMPLE 3 Use a trigonometric ratio to find a hypotenuse
sin 35o = opp. hyp. 11 sin 35o = x x sin 35o = 11 x = x 11 11 sin35o 0.5736 ANSWER You will need a little more than 19 feet of cable. x 19.2 EXAMPLE 3 Use a trigonometric ratio to find a hypotenuse SOLUTION Write ratio for sine of 35o. Substitute. Multiply each side by x. Divide each side by sin 35o. Use a calculator to find sin 35o. Simplify.
0.6, 0.8 0.8824, 0.4706 about 15.7 ft ANSWER ANSWER ANSWER 5. In Example 3, use the cosine ratio to find the length of the other leg of the triangle formed. for Examples 2 and 3 GUIDED PRACTICE In Exercises 3 and 4, find cosRand cosS. Write each answer as a decimal. Round to four decimal places, if necessary.