Introduction to Primary Trig Ratios

Today in grade 10 we looked at right angle trigonometry. The initial prompt was to use a ruler and protractor and draw a right angle triangle that has an angle of 30 degrees.

The next prompt was to measure each side, and record the values in the chart on the wall. The headings were “small side” “middle side” and “long side”.

Next I used my magical skills to tell everyone which triangles were perfectly drawn and measured.

My students know I’m not magic, so they were trying to figure out the trick or pattern I was using.

Pretty quickly they concluded that the small side was half the length of the longest side.

This is how we started the discussion about trig ratios. I showed them a trig table book from 1965 that was used at KCVI before the age of calculators.

We explored how we can use calculators to solve for missing sides and angles. It’ll take more practice, but we’re well on our way to solving right triangles now!