Download Presentation
## Chapter 4 Angles and their measures

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Degrees vs Radians**What do you know about degrees? What do you know about Radians?**Degrees**Degree is represented by the symbol . It is a unit of angular measure equal to 1/180th of a straight angle. In DMS (Degrees-minutes-second) system of angular measure, each degree is subdivided into 60 minutes and each minute is subdivided into 60 seconds.**Example:**A) Convert B) Convert**How to do it for A:**• A) First we convert • Then we have to convert .5 minute into seconds So the answer is**How to do it for B:**Each minute is 1/60th of a degree and each second is 1/3600th of a degree So it is**Navigation**In navigation, the course or bearing of an object is sometimes given as the angle of the line of travel measured clockwise from due north.**What is Radian?**A central angle of a circle has measure 1 radian if it intercepts an arc with the same length as the radius.**Example Working with Radian Measure**How many radians are in 60 degrees?**Group Work:**How many radians are in 90 degrees? How many degrees are in**Arc Length Formula (Radian Measure)**You may seen this as**Arc Length Formula (Degree Measure)**You may seen this as**Note:**So basically, when you find the arc length of a circle, you are finding the radian!!**Angular and Linear Motion**Angular speed is measured in units like revolutions per minute. Linear speed is measured in units like miles per hour.**Example:**You have a car, it’s wheels are 36 inches in diameter. If the wheels are rotating at 630 rpm, find the truck’s speed in miles per hour**Answer**67.47 mi/hr Note remember 1 radian = the radius**Nautical Mile**A nautical mile (naut mi) is the length of 1 minute of arc along Earth’s equator.**Statute mile**Statue mile is the “land mile”**Example**From Boston to San Franciso is 2698 stat mi, convert it to nautical mile.**Homework Practice**P 356 #1-39 every other odd**Trigonometric Functions, special right triangles and the**unit circle**Day 1**Exploration activity! You are to cut out the unit circle I provided onto the notebook. You are to trace as many special right triangle onto the unit circle as possible, but here is the rule. The hypotenuse of the triangle must be the radius of the circle and one leg on the axis. Hint: You should have 3 per quadrant After tracing it all, find the coordinates of the points that lies right on the circle and find the cumulative degrees of each point on the circle. Then answer the following questions in your group**Day 1**Why is it called a unit circle? How does the special right triangles and unit circle relate? What does the special right triangles give you relating to the circle? Is it possible to convert the degrees into radians? How do you do it?**Unit Circle**The unit circle is a circle of radius 1 centered at the origin.**Review**SOHCAHTOA**Practice***Teacher make up different problems regarding SOHCAHTOA**Note:**Please remember the unit circle and the coordinates with its radian/degrees In an Unit Circle, the radius r is 1 is the degree or radians Also please note that (X,Y) is a rectangular coordinate In the unit circle with regarding to Trig: (X,Y) = ) X is Y is**Practice Using Unit Circle***Teacher make up different practices regarding Unit Circle**Trigonometry Extension**sin csc cos t**Practice**Teacher make up different practices regarding the 6 trigonometry functions**Coterminal Angles**Two angles in an extended angle-measurement system can have the same initial side and the same terminal side, yet have different measures. Such angles are called coterminal angles.**Example Evaluating Trig Functions Determined by a Point in**QI**Example Evaluating Trig Functions Determined by a Point in**QI**Homework Practice**P 366 #1-55 EOO P 381 #1-48 EOE