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Unit 6 Lesson 6 Trigonometric Ratios. CCSS. Lesson Goals. Understand the three basic trigonometric ratios are based on the side lengths of a right triangle. Write the three basic trigonometric ratios in fractional and decimal form.
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Unit 6 Lesson 6Trigonometric Ratios CCSS Lesson Goals Understand the three basic trigonometric ratios are based on the side lengths of a right triangle. Write the three basic trigonometric ratios in fractional and decimal form. Use a chart or calculator to find the three basic trig ratios for a given angle. G-SRT 6: Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles. G-SRT 7: Explain and use the relationship between the sine and cosine of complementary angles. G-SRT 8: Use trigonometric ratios and the Pythagorean Theorem to solve right triangles in applied problems. ESLRs: Becoming Effective Communicators, Competent Learners and Complex Thinkers
Ratios compare two quantities by division In a right triangle, the hypotenuse is the side opposite the right angle. The word “adjacent” means “next to” Previously in math hypotenuse Room 12 is adjacent to Room 11
Definition Trigonometric Ratio A ratio formed by comparing the lengths of two sides of a right triangle from the “viewpoint” of a given acute angle. • Sine: leg length opposite an angle to the hypotenuse • Cosine: leg length adjacent an angle to the hypotenuse • Tangent: leg length opposite an angle to the leg length adjacent the angle
You Try B A C
You Try B A C
Definition B A C
Definition B A C
The Gabrielino–TongvaIndian Tribe that at one time lived in the area which we now know as Fullerton used the word SOHCAHTOA to help them remember the trigonometric ratios. Sine Opposite Hypotenuse Cosine Adjacent Hypotenuse Tangent Opposite Adjacent Trigonometric Ratio Bird Dancers Gabrielino/Tongva Indians of So Cal
Example B 13 5 A C 12
Example B 1 A 1 C
Definition Trigonometric Identities An equation involving trig ratios that is true for all acute angles. • qis the “x” for angles
A Example 5 3 B 4 C
A Proof c b B a C statement reason
Trigonometric Ratios • Every acute angle has a sine, cosine, and tangent. • These ratios are usually written as a four-digit decimal approximation. • These ratios can be looked up in trigonometric tables or found with a scientific calculator.
Page 845 also the last page of your notes.
Example = 0.5592 sin 34o
Example = 2.1445 tan 65o
Example Using a scientific calculator.
Summary What is meant by the sine, cosine, and tangent of an angle?
Today’s Assignment • p. 562: 10 – 20 e, 47, 48
Use a Trig Ratio Table or a calculator to find each value. Use your knowledge of a 30-60-90 right triangle.