2. YYou must remember the Pythagorean Theorem a² + b² = c² and that it only works on right triangles. YYou must also be able to identify triangles as being acute, right, or obtuse. If c² > a² + b² then it is obtuse. If c² ˂ a² + b² then it is acute. PPractice problems Page 420 1-6all, 10- 15all, 18-29all

3.  45-45-90 triangles s√2 s s  30-60-90 triangles 2s s s√3  Practice problems Page 428 1-6all, 9-14all, 17-22all

4.  You need to know the Tangent Ratio  Remember this trig function only works on right triangles  If I ask for a ratio, I only want a fraction but make sure it is in simplest terms (reduce it)  Tan ∠ = opposite/adjacent  If you are trying to find an angle then you use tan͞ ¹,which is tangent inverse.  You need to decide, based on the given information which trig function to use and what order to put the information in.  Make sure you have a calculator that has trig functions on it and know how to use it.  Practice problems Page 434 1-9all, 11-20all, 27-29all.

5.  You need to know both the Sine and the Cosine Ratios  Remember that these trig functions only work on right triangles  If I ask for a ratio, I only want a fraction but make sure it is in simplest terms (reduce it)  Sine (sin) Sin ∠ = opposite/hypotenuse  Cosine (cos) Cos∠ = adjacent/hypotenuse  If you are trying to find an angle, then you would use either sin⁻¹ or cos⁻¹, which is sine inverse or cosine inverse, respectively  You have to decide, based on the information given which trig function to use and what order to put the information in  Make sure you have a calculator that has trig functions on it and know how to use it  Practice problems Page 441 1-9all, 11-16all, 22-24all

6. AAn angle of elevation is from the point of view the object has. So, if the object is looking up then it is an angle of elevation AAn angle of depression is from the point of view the object has. So, if the object is looking down then it is an angle of depression IIt helps that the lines are parallel because then the angles are alternate interior which means that they are congruent. You can then figure out the measurements of the missing side using the trig functions that you just learned PPractice problems Page 447 1-10all, 12, 13