### Your thinking...What trigonometry might be? What is the opposite side? Or What should I use in this problem? Sine, Cosine, or Tangent? What is the difference between sin 48? and sin-1(.7431)? How to solve for x, or how to find the side in the triangle? ... How do I read a table with sine, cosine and tangent ratios, and angles? How should I read a graph to find sine or cosine?

### We really try to give you the easiest way of answering all those questions. The presentation of concepts and solution of problems privilege animations, sequence, and colors over long paragraphs difficult to understand. One alternative each time an example is shown is that you will be allowed to solve very similar problems on the screen with the marker tools menu and writing the solution on the screen (Stylus). You will feel very supported all along the lesson!

** Lesson's Content **

** Lesson's Glossary **

**Angle **

Geometric shape formed by two rays (initial and ending sides of the angle) that share a common endpoint called the vertex. You may name an angle using the vertex, or a point in each ray and the vertex label in the center.

**Angle of Elevation is the angle formed by the straight oblique line connecting a point in the horizontal and a point above the horizontal. As viewed by one observer for whose eye the horizontal is drawn.**

**Angle of depression is the angle formed by the straight oblique line connecting a point in the horizontal and a point below the horizontal. As viewed by one observer for whose eye the horizontal is drawn.**

**Cosine **

Ratio determined by the hypotenuse in a right triangle and a side adjacent to a reference angle.

Hypotenuse

The side opposite the right angle in a right triangle.

**Proportion **

A statement that two ratios are equal.

Proportional

One of four numbers that form a true proportion.

**Pythagorean theorem a2 + b2 = c2.**

The Pythagorean theorem states that if you have a right triangle, then the square built on the hypotenuse is equal to the sum of the squares built on the other two sides.

**Ratio **

A quotient of 2 numbers.

**Sine**

Ratio of the length of the opposite side to a reference angle in a right triangle and the hypotenuse. Opposite/hypotenuse.

** Tangent**

The ratio of the length of the opposite side of a reference angle to the adjacent side to the same angle. Opposite over adjacent.

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