## Week 16 – Grade 10 Trigonometry Review

This week we spent some time reviewing trigonometry from grade 10, so that we would be refreshed for our trigonometry unit this year.

Important things to remember:

3 main ratios in trig are Sine (sin), Cosine (cos), and Tangent (tan)

An abbreviation we use to remember this is SohCahToa

SohCahToa is used to find angles of right triangles.

For example: H=8, O=4. Find angle x.

This diagram labels the hypotenuse, opposite and adjacent, but not all diagrams are labeled. Too figure out which is which is easy!

Hypotenuse will always be your longest side, and is usually straight across from your right angle.

Adjacent is the side directly connecting your right angle and missing angle.

Opposite is the side leftover or directly across from the missing angle.

In our abbreviation Soh Cah Toa: “S” stands for Sine, “C” stands for Cosine and “T” stands for Tangent. Other than these, your smaller letters all stand for something: Your “o”pposite, “h”ypotenuse and “a”djacent.

Knowing where each side is can help us dictate whether to use Sine, Cosine or Tangent to solve for the angle.

In our diagram, we’re given the length of the hypotenuse and the opposite. Knowing that we decide to use “Soh” from our abbreviation because it’s the only one with opposite and hypotenuse.

To find the angle we use the “sin” button on our calculator, but the inverse function of it because we’re solving for the angle and not a side.

When punched in the equation should look like

If you were instead solving for a side, the regular “sin” button would be used instead.