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Learn how to find cosine and sine, use a calculator for trig functions, and calculate latitudes on Earth. Homework questions included.
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The terminal side passes through (1, -2), find cosƟ and sinƟ. • The sine of an angle is . The angle is in Quadrant II. What is the cosine of the angle? • The cosine of an angle is . The angle is in Quadrant IV. What is the sine of the angle? • Solve in radians: cosƟ= 0 Warm Up
Period: Amplitude: 1 Domain: Range: Sine Graph
Period: Amplitude: 1 Domain: Range: Cosine Graph
Locate on your unit circle. How far is from the x-axis? is the reference angle. Locate -240 ̊on your unit circle. How far is -240 ̊from the x-axis? 60 ̊ Reference Angles 60 ̊ is the reference angle.
Reference Angles Find the reference angle for each angle 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 48.4 37 24 3 10 25
Expressing a Trig Expression in Terms of a Reference Angle Ex: Express sin 695 ̊ in terms of a reference angle. 1. Locate the angle on the unit circle. IV 2. What quadrant is it in? Is the sin/cos value positive or negative in that quadrant? Negative 25 ̊ 3. Find the reference angle. 3. Write your answer: sin 695̊ = -sin25 ̊
sin 170 ̊ 2. sin(-15 ̊) 3. sin 400 ̊ 4. cos 160 ̊ 5. cos 182 ̊ 6. cos (-100 ̊) sin 10 ̊ -sin 15 ̊ sin 40 ̊ -cos 20 ̊ Give each of the following in terms of a reference angle. -cos 2 ̊ -cos 80 ̊
Sine and Cosine on the Calculator Before doing any calculations involving trig functions always check the calculator mode. How to use your calculator to find sin and cos
Make sure to check the mode then evaluate the expressions below:
The latitude of a point on Earth is the degree measure of the shortest arc from that point to the equator. For example, the latitude of point P in the diagram equals the degree measure of arc PE. Latitude E
The Latitude of Rome is approximately 42N The radius of earth is approximately 3963 miles = 2905 miles How far is Rome from the equator?
The Latitude of Durham is approximately 36 N The radius of earth is approximately 3963 miles Durham is 90 ̊- 36 ̊= 54 ̊ from the North Pole How far is Durham, North Carolina from the North Pole? = 3735miles
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