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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 H omework : Chapter 8 Take Home Test; Due Thursday Announcements:. Finding sides from angles.
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Geometry 4/7/14 • Obj: SWBAT use trig ratios • Chapter 8 Take Home Test • Agenda • Bell Ringer: Go over Quiz • pg450 #4-8 • Homework Requests:pg 699 #1-4, pg 694 #1-14 • Homework: • Chapter 8 Take Home Test; Due Thursday • Announcements:
Finding sides from angles Introduction to Trigonometry
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
Ratio Name sine cosine tangent cotangent secant cosecant Abbreviation sin cos tan cot sec csc The ratios have names and abbreviations…
The Trigonometric (trig) ratios: FUNCTION INVERSE FUNCTION
Here we name one angle Theta Is the Greek letter Theta
opposite adjacent 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. c The sacred Jedi word: b SOHCAHTOA SOHCAHTOA INE a ANGENT OSINE PPOSITE DJACENT PPOSITE DJACENT YPOTENUSE YPOTENUSE
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
You try: • Find the hypotenuse length and the values of the 5 other trig functions for: Hint: use a2 + b2 = c2 to find the hypotenuse!
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.