# Week 17

This past week in Pre Calculus 11 we continued Chapter 6: Trigonometry. Something I learned was special triangles. There are two special triangles, one that is an equilateral triangle that was split down the middle and the other is a rectangle that was split diagonally in half. Below is both the triangles with their dimensions:

Questions would potentially ask sin315 and in the quadrants listed above you find 315 in one of the quadrants which happens to be in quadrant 4 which is in the rectangle special triangle. Sine is opposite/hypotenuse so from angle 45 degrees you find the opposite which is 1 and the hypotenuse which is root 2, at this point the answer is $\frac{1}{\sqrt{2}}$ .

One other part you have to consider is it negative or positive:

315 degrees in highlighted and it is found in quadrant 4, since cosine is the only one that is positive in this quadrant then the $\frac{1}{\sqrt{2}}$ becomes negative –> $-\ \frac{1}{\sqrt{2}}$ .