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## Geometry (all content)

### Course: Geometry (all content)>Unit 13

Lesson 8: The reciprocal trigonometric ratios

# Trigonometric ratios review

Review all six trigonometric ratios: sine, cosine, tangent, cotangent, secant, & cosecant.

## What are the trigonometric ratios?

sine, left parenthesis, angle, A, right parenthesis, equalsstart fraction, start color #11accd, start text, o, p, p, o, s, i, t, e, end text, end color #11accd, divided by, start color #e07d10, start text, h, y, p, o, t, e, n, u, s, e, end text, end color #e07d10, end fraction
cosine, left parenthesis, angle, A, right parenthesis, equalsstart fraction, start color #aa87ff, start text, a, d, j, a, c, e, n, t, end text, end color #aa87ff, divided by, start color #e07d10, start text, h, y, p, o, t, e, n, u, s, e, end text, end color #e07d10, end fraction
tangent, left parenthesis, angle, A, right parenthesis, equalsstart fraction, start color #11accd, start text, o, p, p, o, s, i, t, e, end text, end color #11accd, divided by, start color #aa87ff, start text, a, d, j, a, c, e, n, t, end text, end color #aa87ff, end fraction
cotangent, left parenthesis, angle, A, right parenthesis, equalsstart fraction, start color #aa87ff, start text, a, d, j, a, c, e, n, t, end text, end color #aa87ff, divided by, start color #11accd, start text, o, p, p, o, s, i, t, e, end text, end color #11accd, end fraction
\sec, left parenthesis, angle, A, right parenthesis, equalsstart fraction, start color #e07d10, start text, h, y, p, o, t, e, n, u, s, e, end text, end color #e07d10, divided by, start color #aa87ff, start text, a, d, j, a, c, e, n, t, end text, end color #aa87ff, end fraction
\csc, left parenthesis, angle, A, right parenthesis, equalsstart fraction, start color #e07d10, start text, h, y, p, o, t, e, n, u, s, e, end text, end color #e07d10, divided by, start color #11accd, start text, o, p, p, o, s, i, t, e, end text, end color #11accd, end fraction

## Practice set 1: sine, cosine, and tangent

Problem 1.1
• Current
sine, left parenthesis, angle, B, right parenthesis, equals
Use an exact expression.

Want to try more problems like this? Check out this exercise.

## Practice set 2: cotangent, secant, and cosecant

Problem 2.1
• Current
cotangent, left parenthesis, angle, B, right parenthesis, equals
Use an exact expression.

Want to try more problems like this? Check out this exercise.

## Want to join the conversation?

• Why aren't the reciprocal functions taught with the normal three?
Are they simply less used or are they harder to teach without sin, cos, and tan?
• Both. They are less used and without the 3 foundational functions, they are a touch harder to teach. We often teach using SOH-CAH-TOA and using a right triangle, so sin/cos/tan are very well known.
• Are cse, sec and cot in a calculator?
• Sometimes. There are also sometimes inverses of all of them, AND hyperbolic versions of all of those!
• what would be some applications for using the inverse functions? BW- they seem more intuitive then the sine, and cosine. Tangent seems more intuitive too.
• Do you mean the "Reciprocal functions" like secant and cosecant. The inverse trigonometric functions (the cyclometric functions) are represented by arcosine, arcsine etc.

Reciprocal functions were used in tables before computer power went up and there are some instances where calculating an inverse of a function is easier than the function.

As to Inverse tringonometric functions they are used to calculate angles.
• Is there an inverse for the reciprocal functions: cosecant, secant, and cotangent?
• Yes, they're arccosecant, arcsecant, and arccotangent.
• why so many weird names, what do they mean, and how do you even pronounce them?
• cot -> cotangent (co-tan-gent), sec-> secant (sea-can't), csc-> cosecant (co-sea-can't)
• What are the hyperbolic trig functions?