12.1 Trigonometric Ratios

This lesson was split into two parts.

Day 1: We looked at the basic trig functions: sin, cos, and tan.

To introduce the tangent we looked at the ratios between the legs of a right triangle that I drew. The drawing was by hand so the ratios weren't perfect, but they were close to a constant. Then I told them that this ratio is important so it has a special name "tan", I let students guess what "tan" was short for and most classes had a student who would guess "tangent".

Then we went over the names for other ratios, i.e. the sine and cosine.

Our angles are in degrees so we need to check our calculators are in degree mode, then we went over how to use the sin, cos, and tan buttons on the calculator.

Day 2: The arcsine, arccosine, and arctan.

I mainly refer to the arc-functions as "inverse sine/cosine/tangent". This is easier, and worked with my explanation of how the inverse functions undo the sine/cosine/tangent.

We went over how to enter these in the calculator and began working on some problems.