Geometry 4714 Obj SWBAT use trig ratios Chapter
Geometry 4/7/14 Obj: SWBAT use trig ratios Chapter 8 Take Home Test Agenda • Bell Ringer: Go over Quiz • pg 450 #4 -8 • Homework Requests: pg 699 #1 -4, pg 694 #1 -14 • Homework: • Chapter 8 Take Home Test; Due Thursday Announcements:
Introduction to Trigonometry Finding sides from angles
Trigonometry is… • A branch of geometry used first by the Egyptians and Babylonians (Iraq) • Used extensively is astronomy and building • Based on ratios between angles in RIGHT Triangles
The ratios have names and abbreviations… Ratio Name sine cosine tangent cotangent secant cosecant Abbreviation sin cos tan cot sec csc
The Trigonometric (trig) ratios: FUNCTION INVERSE FUNCTION
Also true are…
Here we name one angle Theta Is the Greek letter Theta
We could ask for the trig functions of the angle by using the definitions. You MUST get them memorized. Here is a mnemonic to help you. b c opp The sacred Jedi word: SOHCAHTOA osi te a adjacent
If you know the sine, cosine, or tangent of an acute angle measure, you can use the inverse trigonometric functions to find the measure of the angle.
!IMPORTANT! To solve trig functions in the calculator, make sure to set your MODE to DEGREES • Directions: Press MODE, arrow down to Radian Arrow over to Degrees Press ENTER
Example: Find the missing side lengths.
You try: • Find the hypotenuse length and the values of the 5 other trig functions for: Hint: use a 2 + b 2 = c 2 to find the hypotenuse!
Did you get…
Why is this useful? • Imagine being an Ancient Egyptian. They had no calculators, no computers. They could use one angle and a pyramid’s side length to find the other side lengths.
- Slides: 17