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Use Trigonometry with Right Triangles & Define General Angles. Notes 20 – Sections 13.1 & 13.2. Essential Learnings. Students will understand and be able to identify trigonometric ratios. Students will be able to use trigonometric ratios to solve problems.
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Use Trigonometry with Right Triangles & Define General Angles Notes 20 – Sections 13.1 & 13.2
Essential Learnings • Students will understand and be able to identify trigonometric ratios. • Students will be able to use trigonometric ratios to solve problems. • Students will be able to define general angles.
Trigonometry • Comes from the Greek words: Trigonos – triangle Metron - measurement • Bring calculators to every class!
Trigonometry Consider a right triangle with an acute angle θ (theta). Hypotenuse Opposite side θ Adjacent side
Trigonometric Ratios There are six trigonometric functions: Sine Cosecant Cosine Secant Tangent Cotangent
Example 1 Evaluate the trig functions. sin θ = _____ cscθ = _____ cosθ = _____ sec θ = _____ tan θ = _____ cot θ = _____ 17 8 θ 15
Example 2 Evaluate the trig functions. sin θ = _____ cscθ = _____ cosθ = _____ sec θ = _____ tan θ = _____ cot θ = _____ 2 θ 4
Class Problem Find the missing side then find the ratios for θ. sin θ = _____ cscθ = _____ cosθ = _____ sec θ = _____ tan θ = _____ cot θ = _____ 25 θ 7
Example 3: Finding Angles To find the angle, use inverse trig functions: sin-1θ cos-1θ tan-1θ Find angles A and B.
Example 4: Solving Triangles Solving a triangle means finding all of the missing angles and sides.
Example 5 You are measuring the height of a building that is 22 feet away. The angle of elevation from you to the top of the building is 58°. What is the height?
Class Problem A kite makes an angle of 64° with the ground. If the string on the kite is 30 feet, how far above the ground is the kite? (Round to the nearest foot.)
Vocabulary Standard Position Angles – an angle in the coordinate plane rotated counter clockwise from the positive x-axis Initial Side– the side on the positive x-axis
Vocabulary Terminal Side – the side of the angle that is rotated Coterminal Angles – two angles that share the same terminal side
Example 6 Draw an angle with the given measure in standard position. a) 45 b) 405
Example 6 cont. Draw an angle with the given measure in standard position. c) - 45 d) - 570
Example 7 Find a positive and negative coterminal angle with 230. Positive: Negative: There is an infinite number of coterminal angles.
Class Problems • Draw a 420 angle in standard position. • Find a positive and negative coterminal angle with 135.
Assignment Page 856: 3 – 15 (x3), 17 – 19, 21 Page 862: 3 – 9 (x3), 15, 18 WS 1 – Right Triangle Trigonometry