Lesson 4
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1. Lesson 4
1.7. Explore 3
Module 4: Foundations of Trigonometry
In previous mathematics courses you learned the three trigonometric ratios of sine, cosine, and tangent.
Three other trigonometric ratios are used in mathematics: cosecant, secant, and cotangent. They are the reciprocals of sine, cosine, and tangent.
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Just as there are abbreviations for sine, cosine, and tangent, there are abbreviations for the reciprocal trigonometric ratios.
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Read “Example 1” on page 193 of the textbook. Note the following while reading.
- cos θ and sin θ are the x- and y-coordinates of point A.
- To find tan θ, divide the two coordinates,

- csc θ, sec θ, and cot θ are the reciprocal ratios, so take the reciprocal of sin θ, cos θ, and tan θ to find these ratios.
Self-Check 2
Determine the three reciprocal ratios for point P
on the unit circle.
Answers
Can you use the answers from Self-Check 1 to help you complete this question?