http://www.ck12.org Chapter 8. Right Triangle Trigonometry
8.6 Sine, Cosine, Tangent
Here you’ll learn what the three trigonometric ratios are and how to find their value for a right triangle’s non-right
angle.
What if you were given a right triangle and told that its sides measure 3, 4, and 5 inches? How could you find the
sine, cosine, and tangent of one of the triangle’s non-right angles? After completing this Concept, you’ll be able to
solve for these trigonometric ratios.
Watch This
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/52517CK-12 Foundation: Chapter8SoneCosineTangentA
Watch the parts of the video dealing with the sine, cosine, and tangent.
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/1365James Sousa: Introduction to Trigonometric Functions Using Triangles
Guidance
The word trigonometry comes from two words meaningtriangleandmeasure. In this lesson we will define three
trigonometric (or trig) functions.
Trigonometry:The study of the relationships between the sides and angles of right triangles.
In trigonometry, sides are named in reference to a particular angle. The hypotenuse of a triangle is always the same,
but the termsadjacentandoppositedepend on which angle you are referencing. A side adjacent to an angle is the
leg of the triangle that helps form the angle. A side opposite to an angle is the leg of the triangle that does not help
form the angle. We never reference the right angle when referring to trig ratios.