This week we started our trigonometry unit. This was one of the highlights of math ten for me. This week we reviewed the acronym of SOH CAH TOA, this helps me remember which formula to use when finding a side of a right triangle.

sine = opposite/hypoteneuse

cosine = adjacent/hypoteneuse

tangent = opposite/adjacent

We reviewed how to find theta or an unknown angle using the inverse sine, cosine or tangent. And isolating our unknown variable like we know how to do from the solving unit. We then looked at drawing right angle triangles in circles. We would connect our 4 quadrants of a graph with a circle and starting from the center we would draw our reference angle out to the edge of the circle becoming our radius. And at the tip of our reference angle is our reference point written as a coordinate : (#,#). The first number shows the x axis or the adjacent side and the second number shows the y axis or the opposite side. This reference angle formula can be known now as:

sine = y/radius

cosine = x/radius

tangent = y/x

This is how we can look at triangles in quadrant one. Using negative numbers we can assess triangles in all quadrants of the graph. We learned a new acronym for looking at the signs of numbers in each quadrant: All Students Take Calculus, ASTC. This means that in quadrant one all equations will be positive. In quadrant 2 sine will be positive, in quadrant 3 tangent will be positive and in quadrant 4 cosine will be positive.