Second Semester Geometry

Survival Guide

Chapter 8: Trigonometry

Key Ideas

  • Pythagorean Theorum
  • SOH-CAH-TOA Trigonomic Device
  • Inverse ""
  • Degree and Radian Measures
  • Special Right Triangles
  • Unit Circle

Pythagorean Theorum

A squared + B squared = C squared (base squared + height squared = hypothenuse [longest side])

  • Only works on right triangles

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Trigonometric Ratios

  • The sides and the angles of triangles and the trigonometric functions are related.
  • Shows what the missing side measure is

Inverse Trigonometric Functions

  • Shows what the missing side measure is
  • Sets it up like the picture shown

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Angle of Elevation/Depression

  • Deals with viewpoint of people/things
  • Used to find out how high or at what angle things are at

6 Trig Functions

Pretty straight forward. The formulas are in the picture. They are sine, cosine, tangent, cosecant, secant, and cotangent.
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Degree and Radian Measures

You can measure with both degrees and radians. In a unit circle, there are degrees and radians. The degree is obviously the angle measure of each angle, and the radian measure is what it is in terms of Pi.

  • To rewrite a degree measure in radians, multiply be Pi radians over 180 degrees, and the reciprocal of that for radians to degree measure.
  • You use the unit circle in these problems.

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Special Right Triangles

Theorem: In a 30-60-90 triangle the sides are in the ratio 1:2:the square root of 3


  • Use a calculator it makes your life much easier
  • Don't overthink the problem
  • Write out ALL your work

Things We Struggled With

  • The Unit Circle and Radians. That was just hard to understand.
  • Angle of Depression was hard at first, but with practice it got easier.