You may use want to use some mnemonics to help you remember the trigonometric functions. One common mnemonic is to remember the SOH-CAH-TOA.
The sine of an angle is the ratio of the opposite side to the hypotenuse side.
Sine is usually abbreviated as sin. Sine θ can be written as sin θ .
Example:
Calculate the value of sin θ in the following triangle.
Solution:
The cosine of an angle is the ratio of the adjacent side and hypotenuse side.
Cosine is usually abbreviated as cos. Cosine θ can be written as cos θ .
Example:
Calculate the value of cos θ in the following triangle.
Solution:
The tangent of an angle is the ratio of the opposite side and adjacent side.
Tangent is usually abbreviated as tan. Tangent θ can be written as tan θ .
Example:
Calculate the value of tan θ in the following triangle.
Solution:
A review of the sine, cosine and tangent functions
How to find a side using trigonometry?
1. Determine which angle you will work with.
2. Name the three sides of the triangle: Hypotenuse, Opposite and Adjacent.
3. The side you know and the side you are looking for determine which ratio you will use: Sine, Cosine or Tangent.
How to find an angle using trigonometry?
1. Determine which angle you will work with.
2. Name the three sides of the triangle: Hypotenuse, Opposite and Adjacent.
3. The side you know and the side you are looking for determine which ratio you will use: Sine, Cosine or Tangent.
4. Set up the ratio.
5. Solve.
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