Lesson 4
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.
Just as there are abbreviations for sine, cosine, and tangent, there are abbreviations for the reciprocal trigonometric ratios.
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?