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# 5.3 Apply the SINE and COSINE ratios

5.3 Apply the SINE and COSINE ratios. 5.1, 5.3 HW Quiz: Wednesday 5.1-5.3 Quiz: Friday Midterm: Oct. 6. Sine and Cosine Ratios. Are trigonometric ratios for acute angles that involve the lengths of a leg and the hypotenuse of a right triangle. Acute angles measure less than 90 o. B. C. A.

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## 5.3 Apply the SINE and COSINE ratios

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1. 5.3Apply the SINE and COSINE ratios 5.1, 5.3 HW Quiz: Wednesday5.1-5.3 Quiz: Friday Midterm: Oct. 6

2. Sine and Cosine Ratios • Are trigonometric ratios for acute angles that involve the lengths of a leg and the hypotenuse of a right triangle. Acute angles measure less than 90o

3. B C A Sine and Cosine Ratios • Let ΔABC be a right triangle with acute A. The sine of A and cosine of A (written as sinA and cosA) are defined as follows:

4. Sine and Cosine Ratios OPPOSITE HYPOTENUSE ADJACENT HYPOTENUSE

5. Find SINE ratios • Find sinX and sinY. Write each answer as a fraction and as a decimal rounded to four places (the ten-thousandth place)

6. Find COSINE ratios • Find cosX and cosY. Write each answer as a fraction and as a decimal rounded to four places.

7. Extra Practice • Find sinA and sinB.

8. Extra Practice • Find cosA and cosB.

9. Find side lengths using SINE and COSINE • Find x. Round to the nearest tenth.

10. Extra Practice • Find the value of x. Round to the nearest tenth.

11. Homework • P. 166-167 #1-12, 15-17, 21-26

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